Add recent checksums (#401)

* Add checksum for Hadoop 3.3.1
* Set the Hadoop 3.2.2 as default in muchos.props.example
* Fix a minor typo in muchos.props.example
* Add checksum for ZooKeeper 3.7.0
* Add checksums for Spark 3.0.2, 3.1.2, 2.4.8
diff --git a/conf/checksums b/conf/checksums
index 9dd58e6..7fd34c3 100644
--- a/conf/checksums
+++ b/conf/checksums
@@ -11,6 +11,7 @@
 fluo:1.2.0:037f89cd2bfdaf76a1368256c52de46d6b9a85c9c1bfc776ec4447d02c813fb2
 fluo_yarn:1.0.0:c6220d35cf23127272f3b5638c44586504dc17a46f5beecdfee5027b5ff874b0
 hadoop:3.2.2:054753301927d31a69b80be3e754fd330312f0b1047bcfa4ab978cdce18319ed912983e6022744d8f0c8765b98c87256eb1c3017979db1341d583d2cee22d029
+hadoop:3.3.1:2fd0bf74852c797dc864f373ec82ffaa1e98706b309b30d1effa91ac399b477e1accc1ee74d4ccbb1db7da1c5c541b72e4a834f131a99f2814b030fbd043df66
 hadoop:3.3.0:9ac5a5a8d29de4d2edfb5e554c178b04863375c5644d6fea1f6464ab4a7e22a50a6c43253ea348edbd114fc534dcde5bdd2826007e24b2a6b0ce0d704c5b4f5b
 hadoop:3.2.1:f66a3a4115b8f16c1077d1a198a06854dbef0e4233291712ed08d0a10629ed37
 hadoop:3.2.0:226b6cbdf769467250054b3abdf26df9f05fde44bbb82fe5d12d6993ea848f64
@@ -29,8 +30,11 @@
 hadoop:2.7.6:f2327ea93f4bc5a5d7150dee8e0ede196d3a77ff8526a7dd05a48a09aae25669
 hadoop:2.7.5:0bfc4d9b04be919be2fdf36f67fa3b4526cdbd406c512a7a1f5f1b715661f831
 hadoop:2.6.5:001ad18d4b6d0fe542b15ddadba2d092bc97df1c4d2d797381c8d12887691898
+spark:3.1.2:E7B580BC67356F1B36756B18A95E452307EB3825265616E399B1766124764D6E65AB4C666AD23C93E006D88B6C83A78A7D786BE981B4F20696697860A459879D
+spark:3.0.2:43147B4C2C5C955E896EE369B58B32BA1970D7DC049BD96B4234D8961D12836E51EBE0D77F03A9FDB10CBDBB211FB86CDCA41563E8FF8281D353C55EFD43A044
 spark:3.0.1:07FC6DF224F303EF53189E6082004400D51CD6C2244D1851D90EABBE58404A69FF980BFFE147A5259A34190E1E1C974C72D02470D10A783D2D87F43A8DA0850B
 spark:3.0.0:E955A22D4AC917883BCE7327711F33829818946EDC40F1316F0B651DD15B243DFC2FB345794634B41ABA75F0BE2C1E4E1850331409B367F101BF2D308F463709
+spark:2.4.8:84B52335834F1DC0540D5156F4CCD642A23C3CA130EBD5DC1BC8FBF1CAF0F89B783DA34DABD200A0B6385176BAD3BA4261C2C6639CAFC8CA6B8FFB8D7BB3EA72
 spark:2.4.7:FF75E6DB3C4CA5CECE2A8A26AD7BD8A2C1C46B4F93E8F2922A31E6A8D98274BEDC66BEF3E469E862D249C5439355CCCA83687A20D536A8400F2C058BE553DF57
 spark:2.4.5:17A8B3BD0151E506E2B3C09FFE6F1010FFE1C6B7B906F3A19D357B37098EBD0C3AD91E6501545AE87834B81D2EF07556E5FECCFB7275D1C74533777BC7A5DF3B
 spark:2.4.4:A3E4FDEAD2409C8D1E0F213145ACC3B43788285715EB100DD29B171E6B24012673DDD94BDC612D946764B71CBC8F78BCD93889A4BC60B3136A33CD7E6C4DBC26
@@ -39,6 +43,7 @@
 spark:2.3.3:a5c4a54db5163df25110534f36e13d6ae65758d45d1bc8bfcd7e27304e716a23
 spark:2.3.2:3387107155d62f04ccf6bcaf2e00a69a0de5ae5df875348d93147743c206f0a8
 spark:2.2.2:023b2fea378b3dd0fee2d5d1de6bfaf2d8349aefe7be97a9cbcf03bbacc428d7
+zookeeper:3.7.0:64e2701c019ed46f45f4d53b2c5eaeaf7cf48c342bbafa032a0819d527fc77caebfada6bdad34e5171e6d838f40b16c95b62ce378b53dfc827af2d60cec0b17c
 zookeeper:3.6.3:3f7b1b7d9cf5647d52ad0076c922e108fa956e986b5624667c493cf6d8ff09d3ca88f623c79a799fe49c72e868cb3c9d0f77cb69608de74a183b2cbad10bc827
 zookeeper:3.6.2:caff5111bb6876b7124760bc006e6fa2523efa54b99321a3c9cd8192ea0d5596abc7d70a054b1aac9b20a411407dae7611c7aba870c23bff28eb1643ba499199
 zookeeper:3.6.1:1c5cb4d9886fae41bf244a446dd874b73c0fff7a5fc2dda4305041964420cde21e59b388dfd2551464a46bb6918d9d3c3c01ebe68fdbe782074ee360aa830c7d
diff --git a/conf/muchos.props.example b/conf/muchos.props.example
index 7449807..a7eda49 100644
--- a/conf/muchos.props.example
+++ b/conf/muchos.props.example
@@ -36,9 +36,9 @@
 # Accumluo Password
 accumulo_password = secret
 # Software versions (make sure you have a corresponding entry for the checksum in conf/checksums)
-hadoop_version = 3.2.1
+hadoop_version = 3.2.2
 zookeeper_version = 3.6.3
-spark_version = 2.4.5
+spark_version = 2.4.8
 fluo_version = 1.2.0
 fluo_yarn_version = 1.0.0
 accumulo_version = 2.0.1
@@ -55,7 +55,7 @@
 # Give a logical name for the cluster, all one word no special characters. Required to support HDFS HA.
 nameservice_id = muchoshacluster
 # number of accumulo tablet servers to run per host. This is only effective when systemd is set to 'True'. Needs changes in
-# accumulo-service script inorder to support non-systemd cases.
+# accumulo-service script in order to support non-systemd cases.
 num_tservers = 1
 # If accumulo services are to be run under systemd, set this to 'True'
 use_systemd = False