JBIDE-16910: add missing IUs to allow installation of Atlassian; remove uninstallable GPE feature as it's not compatible w/ Luna
JBIDE-16910 revise instructions for validating TP using tycho-plugins fix-versions; then mvn install to ensure it's resolvable; and finally p2.director to perform an installation
add 4 com.google.gwt/gdt plugins so that org.jboss.tools.maven.gwt.feature can be installed (JBIDE-16960)
JBIDE-16960 remove com.google.gwt.eclipse.* from JBT TP 4.40.0.Beta2-SNAPSHOT
update README
Update README.md
JBIDE-17019: add m2eclipse-egit

We want m2eclipse-egit to be
* installed by default with JBT => so goes to JBT TP
* part of JBDS delivery => so goes to JBDS TP