Support hex encoding for :varbinary as well as :binary

in abstract_mysql_adapter

Copied from 518076f5a9d14909ee082b2f71825df9573cd0ce in the web repo
Leave triggers alone when loading fixture from yaml
Merge branch 'jpt/ruby2_invocaisms' into cdk/leave_triggers
Remove drop_triggers! entirely
Include triggers in db:structure:dump
Merge pull request #5 from Invoca/cdk/leave_triggers

Serialize triggers in schema files