Adds a kepler profile to the build

For when we need a kepler only build
Don't use internal classes for matchers.
Restore contents of file after test, to make it order-independent.
Add specific type annotation to work around Scala bug SI-5559.
Depend on mockito-core instead of mockito-all in the integration test projects.
Additionally, exclude dependency on org.hamcrest:hamcrest-core.

This fixes test failures on Kepler caused by conflicting versions of
hamcrest-core present on classpath: version 1.1 embedded in mockito-all and
version 1.3 pulled in as P2 dependency.
(cherry picked from commit 4e2ff88760b2326fa09ea946877af73110645f90)
Fixes a timing problem in one debug test
Fix order-dependent tests and continuation tests

* don't use `defaultPluginsDir.foreach`, since the type change
from `Option[String]` to just `String`. Strangely enough, the
expression still type-checked, using `Char => Unit`, and calling
the wrong `PropertyStore` overload, leading to failures
* reset the presentation compiler before checking for loaded
plugins
* some tests fail if they are run in a different order,
based on some side-effects (class path changes, property
store changes). Fixed it.
Implement completion overwrites

Allow completions to overwrite existing code. The user can
toggle between insert and overwrite modes by pressing `Ctrl`,
just like in the Java editor. This also respects the Java
editor option for preferring inserts always.

In addition to replacing the existing identifier, we also suppress
the linked mode for arguments (since likely the existing arguments
are not valid, but also we can't erase them, as they may be useful).
This is the same behaviour as in the Java editor

Fix #1000569
Merge pull request #445 from dragos/issue/completion-overwrites

Implement completion overwrites
Merge pull request #460 from skyluc/master-builds-against-kepler

Updates to allow compilation against Kepler (and Juno)
Add scala-xml and scala-parser-combinator dependencies for the 2.11.x profile.
Remove unnecessary xml dependency from test
Merge pull request #464 from dragos/fix/modularization

Fix the build for 2.11