[Fix #1214] Require one key per line for inspection in AlignHash

If some keys don't begin their line, we quit the inspection of
that hash.
Merge pull request #1218 from jonas054/fix_1214

[Fix #1214] Require one key per line for inspection in AlignHash
Add support for string source in EndOfLine cop

`ProcessedSource` supports string sources, but `EndOfLine` cop would fail. This
ensures that `EndOfLine` cop supports strings.

* expose original source of `ProcessedSource`
* simplify `EndOfLine` cop logic