Bump version in POMs to 2.3.7-SNAPSHOT

After release of 2.3.6 bump the version in POMs from 2.3.6 to 2.3.7-SNAPSHOT.
6 jobs for master in 1 minute and 8 seconds (queued for 10 seconds)
latest
Status Job ID Name Coverage
  Build
passed #35239
jars-j8

00:00:22

failed #35238
java8-sonar

00:00:45

 
  Test
skipped #35240
allowed to fail
java7
skipped #35242
allowed to fail
maven36-java11
skipped #35243
allowed to fail
maven36-java13
skipped #35241
allowed to fail
maven36-java8
 
Name Stage Failure
failed
java8-sonar Build
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:415)
at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:356)
32818 [ERROR]
32818 [ERROR] Re-run Maven using the -X switch to enable full debug logging.
32818 [ERROR]
32818 [ERROR] For more information about the errors and possible solutions, please read the following articles:
32819 [ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException
Cleaning up file based variables
ERROR: Job failed: exit code 1