Added invite migration and model
Added authentication (matching key and secret)
changed #leave test
#delete_if_empty tests passing
Started mailer configuration (awaiting Sendgrid approval)
Merge branch 'email-invites'
Merge branch 'master' of https://github.com/inoda/you-owe-me-homie into pending-table
added pending and denied tables for transaction history and started adding tab interface design for transaction history