fixed karma's autoWatch (closes #9)

Closes 3 bugs using 2 hacks.

#### 1. Fix early restart on test change

Test scenario

1. Change test file to `throw new Error('foo')`.
2. Wait for recompilation.
3. Change test file to `throw new Error('bar')`.

Expected: test is failed with `bar` message.
Result in v1.1 (afaa7b3f7117c8ebce5dd07d0c9b8dba3250c313): test is failed with `foo` message.

#### 2. Fix ignoring of test dependencies change

Test scenario

1. Change test dependency
2. Wait for recompilation

Expected: test is run.
Result in v1.1 (afaa7b3f7117c8ebce5dd07d0c9b8dba3250c313): nothing.

#### 3. Fix browser cache

Test scenario

1. Change test dependency
2. Wait for recompilation
3. Karma serves file with the same sha

Expected: browser gets the new file.
Result in v1.1 (afaa7b3f7117c8ebce5dd07d0c9b8dba3250c313): browser uses cached version.
Workarounds: bust browser cache manually / re-open browser.