ISPN-3197 Message ordering of Get and Invalidation can cause L1 to be inconsistent.

* Implemented single entry point for concurrent gets.
* Also support concurrent invalidation for reads with limited blocking
* Added tests for various concurrency/edge issues
ISPN-3325 ConsistentHashV1IntegrationTest.testCorrectBalancingOfKeysAfterNodeKill random failures
Remove references to version.scala in parent pom.xml

Fixes problems with IntelliJ compilation of server modules.
ISPN-2771 WriteSkewTest.testWriteSkewWithOnlyPut fails randomly

* Removed write skew check from put operation. Now, the write skew check
it is only performed during prepare time for local or clustered mode.

* Adapt the local mode tests to support this modification