435692 - Only rebuild dependency projects if they are affected by the change

Fixes #17

Signed-off-by: Anton Tanasenko <atg.sleepless@gmail.com>
436679: ProjectRegistryRefreshJob double work for imported projects Signed-off-by: wecai <wecai@ebay.com>
436668: Avoid ProjectFacade refresh when .classpath or .project changes Signed-off-by: wecai <wecai@ebay.com>

Fixes #19
Merge remote-tracking branch 'upstream/master'

Conflicts:
	org.eclipse.m2e.tests/src/org/eclipse/m2e/tests/ProjectRegistryRefreshJobTest.java


Signed-off-by: wecai <wecai@ebay.com>