epoch table requires additional column

[pendingintent]

Add a 'type' column to the epoch database table.

In migrate_database.py, add new function _migrate_add_epoch_type to add 'type' column to store TEXT.

Call this _migrate_add_epoch_type function when starting the app in app.py

[pendingintent]

Added _migrate_add_epoch_type() to create new column type in epoch table.

This will be added when master merged with branch migrate-epoch-table