Info about getting set up using composer and MAMP

Added by request of Gábor Novoszádi from community feedback and thanks to the gist from @kkirsche. I have supplied a link to the gist as it is well written, with permission we may look to rework for direct inclusion at some point :)
Docs / Tests for Director::absoluteURL
Merge pull request #3011 from tractorcow/pulls/absurl

Docs / Tests for Director::absoluteURL
Add 3.0.10 upgrade docs
Merge pull request #3010 from camfindlay/patch-3

Info about getting set up using composer and MAMP
FIX - missing link url for composer

My bad, have amended this.
Merge pull request #3014 from camfindlay/patch-4

FIX - missing link url for composer
Merge remote-tracking branch 'composer/3.0.10' into 3.1.4
3.1.4 upgrading docs
BUG Fix Date and SS_DateTime::FormatFromSettings
This issue is caused by the odd default behaviour of Zend_Date, which attempts to parse yyyy-mm-dd format date and times as though they were yyyy-dd-mm.
Update upgrading docs 3.1.4
Merge remote-tracking branch 'origin/3.0' into 3.1
Merge remote-tracking branch 'origin/3.1.4' into 3.1