fix(aalborg_theme): standardize padding on input and a buttons

Follow-up of #6591
fix(comments): makes ElggComment E_STRICT compliant

Gives ElggComment::canComment the same signature as the method in
its parent class.
fix(rewrite_tester): more reliably sniffs active rewrite rules

Under certain conditions curl would fail to open localhost URLs where
file_get_contents would handle fine. This tries file_get_contents first
instead of curl.

Fixes #6656
Merge pull request #6658 from mrclay/canCommentStrict

fix(comments): makes ElggComment E_STRICT compliant
Merge pull request #6594 from PerJensen/aalborg_button_css

fix(aalborg_theme): standardize padding on input and a buttons and adds box-sizing
Merge pull request #6659 from mrclay/6656

fix(rewrite_tester): more reliably sniffs active rewrite rules
feature(upgrade): Added ElggUpgrade object.

Refs #6451.