Remove folsom references.

We removed it in the main repo already.

Issue: https://github.com/apache/couchdb/issues/4650
diff --git a/src/ioq.erl b/src/ioq.erl
index f6be488..ca7cae7 100644
--- a/src/ioq.erl
+++ b/src/ioq.erl
@@ -19,7 +19,7 @@
 ]).
 -export([get_io_priority/0, set_io_priority/1, maybe_set_io_priority/1]).
 
--define(APPS, [config, folsom, couch_stats, ioq]).
+-define(APPS, [config, couch_stats, ioq]).
 
 set_io_priority(Priority) ->
     erlang:put(io_priority, Priority).
diff --git a/test/ioq_tests.erl b/test/ioq_tests.erl
index 2e866a4..de3796b 100644
--- a/test/ioq_tests.erl
+++ b/test/ioq_tests.erl
@@ -20,7 +20,7 @@
 
 setup() ->
     Apps = test_util:start_applications([
-        config, folsom, couch_log, couch_stats, ioq
+        config, couch_log, couch_stats, ioq
     ]),
     FakeServer = fun(F) ->
         receive {'$gen_call', {Pid, Ref}, Call} ->