* refactor struct's time to remove unnecessary memory usage

* use AsTimePtr simple code

* fix tests

* fix time compare

* fix template on gpg

* use AddDuration instead of Add

- Fill Milestone and Assignee field when available in webhook payload

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