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.
Merge pull request #460 from skyluc/master-builds-against-kepler

Updates to allow compilation against Kepler (and Juno)