A first step and updating AddOns

And P2Repository support 'file:///...' type URL
Added support to set versions in plugins
Start of some basic documentation
Added mvn command for addons
Compile against Scala 2.9.2
Added some info about the Scala IDE updater
Implementation of creating the update site
Installable units holded by P2Repository are now sorted in descending order

The main consequence is that `P2Repository.findIU` now returns a *sorted*
sequence of `InstallableUnit`, where the most recent one comes first.
Furthermore, `P2Repository.findIU` now expect an exact `unitId` to be passed,
and no longer works with regular expressions (the functionality was removed
because it is not needed).

Also, since we need to compare OSGI Version numbers, I've added a dependency to
"org.osgi" % "org.osgi.core" % "4.3.0", as it provides a `Version` data object
that implementes `Comparable`. This lead to a few changes so use `Version`
instead of a raw string.
More wip
Merge remote-tracking branch 'upstream/master' into wip

Conflicts:
	.classpath
Additional set of changes, using the config support
Merge remote-tracking branch 'mirco/wip' into wip

Conflicts:
	src/main/scala/org/scalaide/buildtools/GenerateEcosystemBuilds.scala
	src/main/scala/org/scalaide/buildtools/P2Repository.scala
Tweaked ecosystem build

Find the newest version of an addon
0.1.0 release
Moved to 0.2.0-SNAPSHOT
Added missing Http.shutdown calls
0.1.1 release
Added a mvn build to be used to mix repos
Set the right project version (snapshot)
Update scaladoc for added 'base' attribute