Allow users to not override default mailer configs

Fix from_address logic in mailers, it broke when there were noe
mail_method record on the database

Fixes #2929
Bump database_cleaner to 0.9.1
Fix StockLocation spec
Revert "Bump database_cleaner to 0.9.1"

Due to randomly failures with SQLite3's locked DB, I have to revert
this commit until database_cleaner sort this out

This reverts commit a726fa2c437e2408d095f6b2b339a61aba3a1ed3.
adding spec and fixing user_logged_in promo rule

Fixes #2884
Wait for API request to complete in stock management spec
Fix remove_fields link from stepping on cocoon

Because the cocoon gem defines a similar callback on 'document', this callback will effectively override it.  
Modified selector scope to ignore cocoon links as a primitive workaround.

Fixes #2853
Revert "Revert "Bump database_cleaner to 0.9.1""

This reverts commit 18095e99e98a47e17e8bed95a62e7bcedfc28bc6.

This was actually happening to some tests not waiting around long enough.