Add sec-bugs plugin. Closes #618 (#628)

* Created build profile for sec-bugs
* Replaced Math.Random with SecureRandom
* Sanitize user input in log messages to prevent potential CRLF injection
* Use SHA-256 instead of MD5 or SHA-1
* Remove unused method in CryptoUtils
* Replace vulnerable regex in Monitor param validation

diff --git a/src/main/spotbugs/exclude-filter.xml b/src/main/spotbugs/exclude-filter.xml
new file mode 100644
index 0000000..e4122bb
--- /dev/null
+++ b/src/main/spotbugs/exclude-filter.xml
@@ -0,0 +1,29 @@
+<!--
+  Licensed to the Apache Software Foundation (ASF) under one or more
+  contributor license agreements.  See the NOTICE file distributed with
+  this work for additional information regarding copyright ownership.
+  The ASF licenses this file to You under the Apache License, Version 2.0
+  (the "License"); you may not use this file except in compliance with
+  the License.  You may obtain a copy of the License at
+
+      http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+-->
+<FindBugsFilter>
+    <Match>
+        <!-- new file on user input can be dangerous but OK here -->
+        <Class name="org.apache.accumulo.maven.plugin.StartMojo"/>
+        <Bug code="PATH" pattern="PATH_TRAVERSAL_IN"/>
+    </Match>
+    <Match>
+        <!-- dangerous on untrusted files but OK here -->
+        <Class name="org.apache.accumulo.maven.plugin.HelpMojo"/>
+        <Method name="build" params="" returns="org.w3c.dom.Document"/>
+        <Bug code="XXE" pattern="XXE_DOCUMENT"/>
+    </Match>
+</FindBugsFilter>