added missing License headers
GROOVY-6074: Use Jar Classloading to complete import statements.

Examples:
groovy:000> import
groovy:000> import j
groovy:000> import java.
groovy:000> import java.net.
groovy:000> import static java.net.

Also complete Classnames for preimported and imported classes

Example:
groovy:000> Sys<tab>

Before: no completion
Afer: completes to System  (from java.lang.System)

Also:
groovy:000> import java.awt.*
groovy:000> Sha<tab>

now completes to "Shape"

As well imported statics:
groovy:000> import static java.lang.Math.*
===> [import static java.lang.Math.*]
groovy:000> ma<tab>

now completes to "max("
Preference to disable import-class-completion
Merge pull request #179 from tkruse/fix_and_imports

complete classpath imports