Signed-off-by: Robin Durner <github@nubenum.de>

* Make sure author cannot reject/approve their own PR

* Disable buttons in templates too

* Remove unneccessary if check since the switch below catches it

* Fix IsOwner check

* Update template and remove new template variable

* Add alert template and redirect to diff page on review failure

* Redirect to files diff as a little update to #4632

This commit improves templates readability, since all of them use consistent
indent with all template command blocks indented too.

1. Indents both HTML containers such as <div>, <p> and Go HTML template blocks
   such as {{if}} {{with}}

2. Cleans all trailing white-space

3. Adds trailing last line-break to each file