java 7 code compatibility

1. try with resources
2. generic diamond inference
3. multi-catch exceptions
Merge pull request #10 from mehiel/java7-compatibility

Take advantage of Java 7 features.

- try with resources
- generic diamond inference
- multi-catch exceptions
Fix configuration methods missing "static".
Merge branch 'java-7' of github.com:jcoleman/tomcat-redis-session-manager into java-7
Bump version to 1.2.
Fix NPE and ensure changes are tracked accurately. Fixes #13.
Merge branch 'java-7' of github.com:jcoleman/tomcat-redis-session-manager
Update README to reflect Java 7 only going forward.
Add optional save-on-change support. Fixes #14.
Rewrite session(id) creation code. Fixes #22. Fixes #23.

* Fix possible infinite looping.
* Fix unnecessary multiple saves to Redis.
* Comply with Manager implementation by returning null if specific session ID is requested but is already taken.
* Fix bug allowing duplicate session IDs.
Don't set the currentSessionId to non-null unless we found the session in Redis. Fixes #25.
Update jedis to 2.5.2. Fixes #34. Fixes #39.
Merge pull request #1 from jcoleman/master

merge newest master
fixed NullPointerException in createSession
Merge pull request #41 from peh/master

Fixed Issue #40
Fix saving when saveOnChange=true.
Add additional README comments re: saveOnChange.
Update license copyright years.
Add commons-pool2-2.2.jar to build.gradle and update jar requirements in README.
Add basic vagrant/rspec/spark integration testing harness.