Add eclipse 3.7 to supported versions in documentation

In the installation guide
http://fusesource.com/docs/ide/2.0/install_guide/install_guide.html

in chapter 1 it lists Eclipse 3.5 and 3.6 as supported versions of Eclipse. It also works with Eclipse 3.7. In fact I do not know if it still works with Eclipse 3.5.

Also we should make a note that currently Spring STS is not supported. But this is subject to change.