Fix Maven POM

1. THRIFT-2269 was not fixed properly. Sources are supposed to be deployed using a "jar" type. maven-dependency-plugin cannot resolve them otherwise and IDEs such as IntelliJ IDEA are unable to resolve or even manually attach sources with a "src" extension/type.

2. Between 0.9.1 and 0.9.2, the POM for libthrift was modified to remove a dependency on commons-lang3. As a result, the code generated by libthrift no longer builds as it misses this dependency. The dependency needs to be restored, or whatever reason resulted in its removal re-evaluated to take this requirement into account. Personally, I'd prefer if we could just drop this dependency entirely and use native Java language utilities such as `Objects` to solve the problems `commons-lang3` is trying to solve.