Change compile java level

[nerro]

In ant build.xml there are 3 specified releases:

• 1.1 java
• 1.4 java
• 1.5 java

I think that minimal version should be changed and compile version too.

[nerro]

java 6 is support only for developers and it's not recommended for using in production. As already java 8 is out I decided to use java 7. Until 4.3 milestone the project will be developed with java 7, but released with java 6 compile level.

With milestone 4.3 the project will required java 7.

[nerro]

oracle highly recommend to use java 7 too.
http://www.java.com/en/download/faq/java_6.xml