Better integration for Android projects.

Instead of just relying on the IDE product code, this checks the
project's assigned SDK and picks an Android-oriented keyword lookup
object instance.  This is needed since recent IntelliJ versions allow
creating Android projects as well as normal Java ones.

As a bonus, the default keyword lookup dataset now contains more
appropriate keywords for JSP/JSPX pages.
New SDK detection logic in place.
sdk context detection