Passing in reactor projects so that we can resolve reactor dependencies.

I believe this finally solves the inability to resolve deps that only exist within the reactor.
NB At the moment it relies on a maven-dependency-tree-2.2-SNAPSHOT which you can build from https://github.com/william-ferguson-au/maven-shared/tree/resolving-reactor-deps

Once I have at least two confirmations that everything is good, I will submit the changes to maven-dep-tree.

I have tested against my projects and against the android-maven-plugin-samples/library-projects. library-projects works fine except there is a  proguard issue with action-bar-sherlock which looks like another issue entirely. Hopefully someone who is more awake than me will work out what is wrong.

In order to test you will need to:
- Build maven-dependency-tree-2.2-SNAPSHOT
- Build/merge this branch and build android-maven-plugin
- Delete from your repository any projects that wil be used in your test (before each run).
- Run your tests.