LANG-1279: Update Java requirement from Java 6 to 7.
LANG-1279: Update Java requirement from Java 6 to 7.

Remove jdk6 from travis configuration.

arbasha/commons-lang,apache/commons-lang,britter/commons-lang,weston100721/commons-lang,MarkDacek/commons-lang,weston100721/commons-lang,britter/commons-lang,arbasha/commons-lang,apache/commons-lang,apache/commons-lang,arbasha/commons-lang,britter/commons-lang,weston100721/commons-lang,MarkDacek/commons-lang,MarkDacek/commons-lang