build: not include not provided deps on pom.xml, scala as provided

[erizocosmico]

Fixes #210

• Not include scala in fatjar
• Mark scala as provided
• Rewrite output pom.xml to remove all dependencies without provided scope and add the scala library as provided (since sbt or something else in the process adds it as compile even if you explicitly put it).

NOTE: this only works for maven repositories. That is, if you use publishLocal, it will not work, you need to use publishM2 and use the local maven repository. Since we deploy on maven it should not matter much.

[bzz]

Let me try it and get back to you asap!

Quick question - do you think reshading more things included in fatJar, on top netty and grpc/guava would not be a good idea in our case?

[erizocosmico]

@bzz reshading is gonna be a pain in the ass and it means every time we add a dependency we need to reshade that as well.
That said, perhaps we should reshade apache commons and jgit that are the most likely to be included. Siva, enry and bblfsh on the other hand, don't think they make sense to reshade them. What do you think?

[erizocosmico]

@bzz just reshaded all apache commons and jgit classes

[bzz]

@erizocosmico tried commit before re-shading and it solved the issue beautifully - thanks a bunch for a prompt fix!