Support powerful/smart commit messages

cf. https://drupal.org/node/2270763

Live example:
```diff
-Issue #2269385 by sun: Fixed DependencyInjection YamlFileLoader is out of date.
+Fix #2269385 by sun: DependencyInjection YamlFileLoader is out of date.
```
---
Problematic / todo:
```diff
-Issue #2254203 by sun: Fix test performance of Drupal\system\Tests\Module\ModuleApiTest.
+Fix #2254203 by sun: Fix test performance of Drupal\system\Tests\Module\ModuleApiTest.
```
should be:
```diff
+Fix #2254203 by sun: Test performance of Drupal\system\Tests\Module\ModuleApiTest.
```
…can't do anything about poor issue titles like that, but _"Fix"_ must not be repeated + title _should_ start capitalized.