Refactor Copy Trans to be more testable.

Correct a previously inserted bug where translations from obsolete documents where not being reused.
Refactor Copy trans to be more functional and thus testable.
Add some tests to test these discrete pieces.
Rename ResultActionPair to MatchRulePair.
Code review changes (See below).

Refactor method to use ternary operator.
Assume a non-nullable argument in copy trans internal method.
Refactor internal MatchRulePair class.
Add @SlowTest annotation.

For now just a marker interface to identify potentially slow running tests.
Change @SlowTest to be a method level annotation.
Merge pull request #154 from zanata/copy-trans-changes

Refactor Copy Trans to be more testable.