Cleanup the migrate command

Reverse change that has caused ridiculous problems.

Spelling: built -> build

Enable deletes with joins in MySQL. Tests.

Added purge method.

Return Illuminate\Support\Fluent when possible, this allow developer …

…to further chain additional command such as ->after() etc.

Signed-off-by: crynobone <crynobone@gmail.com>

Cleaning up code. Fixing stuff. Tests.

Merge branch '4.1' into 4.2

Merge pull request #4547 from ambrella/4.2

[4.2] Gey keyName before instance can be translated into builder

Merge pull request #4604 from GrahamCampbell/4.2-db

Updated Connection Interface