Adding pruning of modules / version conflict manager

This is the first version of the pruning which is similiar to Ivy.
Perhaps we want a more advanced, but static one. See todo in code.
Also added ivy settings which makes it possible to add from typesafe repo
added basic support for configurations. still some issues with ivy
fixed ivy integration. still need to perfect the json format
fixed sbt plugin so that it can work with configurations. must still add support for configs
more flexible json support
now we write json files with the right format (also fixed README)
updated readme
Merge branch 'master' of github.com:freekh/adept into ivy_fixes

Conflicts:
	src/main/scala/adept/Adept.scala
	src/main/scala/adept/ivy/Ivy.scala
	src/main/scala/adept/models/Artifact.scala
	src/main/scala/adept/models/Module.scala
	src/main/scala/adept/operations/Add.scala