Updated p2 bundles in order to support disabling x-installation:=greedy
on imported packages.

+ Updated 'org.eclipse.equinox.p2.core' to version
2.2.0.v20120430-0525.jar
+ Updated 'org.eclipse.equinox.p2.publisher.eclipse' to version
1.1.0.v20120511-1931.jar

More info about support 'greedy' attribute
http://wiki.eclipse.org/Equinox/p2/Publisher#BundlesAction