Initial work to add integration style tests.

The main push of this PR is the fixes required and provision of front to back integration level tests.
The main class is: ```src/test/scala/org/ensime/test/intg/BasicWorkflow```
The goal is to extend this test/create other tests covering more of the system behaviour.

Ideally the integration tests would live in an intg package.  But have been main part of the mainline for now for two reasons:
# but the tools (e.g. scoverage) do not appear to support sbt intg mode
# the unit test coverage is not good enough to be the sole baseline right now.

The goal is to cover the key areas of the protocol so they can be refactored in anger.

This should be cherry-pick with little effort onto 2.10 / 2.9 and we can add flags to ```sbt``` to disable these tests if needed.