INT-2916 - Upgrade to JUnit 4.11 in support of JDK7

For reference see: https://jira.springsource.org/browse/INT-2916

Changes:

* INT-2919 - Upgrade Spring Data Gemfire to 1.2.2.RELEASE
* Exclude Hamcrest transitive dependency from JUnit (as already explicitly declared)
* Set sourceCompatibility in build.gradle to 1.6
* Set targetCompatibility in build.gradle to 1.6
* Upgrade Hamcrest to 1.3 and fix deprications
  - Corematcher is(*class) change to is(instanceOf(*class))
  - Change org.junit.internal.matchers.TypeSafeMatcher to org.hamcrest.TypeSafeMatcher
  - Change import org.junit.matchers.JUnitMatchers.containsString to org.hamcrest.CoreMatchers.containsString
  - Change import org.junit.matchers.JUnitMatchers.both to org.hamcrest.CoreMatchers.both
  - Change import org.junit.matchers.JUnitMatchers.containsString to org.hamcrest.CoreMatchers.containsString
* Fix JUnit deprecations
  - changed junit.framework.Assert to org.junit.Assert
* Add few missing licenses headers to tests
* Marked several test classes with: @DirtiesContext(classMode=ClassMode.AFTER_EACH_TEST_METHOD)
  - SplitterIntegrationTests
  - GatewayInvokingMessageHandlerTests
  - FileToChannelIntegrationTests
  - FileInboundChannelAdapterWithRecursiveDirectoryTests
  - JdbcMessageStoreChannelTests
  - ChatMessageInboundChannelAdapterParserTests
* 3 Tests ignored (Still needs to be addressed):
  - testOperationOnPrototypeBean
  - testFailOperationWithCustomScope
  - testOperationOfControlBus
* Update SQL script (test-failure):
  - spring-integration-jdbc/src/test/java/org/springframework/integration/jdbc/config/outboundSchema.sql
  - add drop table statements
  - add ignore-failures="DROPS" to "jdbcOutboundChannelAdapterCommonConfig.xml"