Alter {users,job_definitions}.id to bigint

[riseshia]

There is the problem that some tables has different type of primary key from its installed:

• before 0.2.0: using unsigned int for primary key
• after 0.2.0: using signed int for primary key

This problem was made by fa75b20e463f0f95d74aa3e50ac6b35e1596f26b.

This makes hard to keep consistency of code / infra. For instance, we need to care about 2 types of primary when adding foreign key. Actually, this is already blocker of https://github.com/cookpad/kuroko2/pull/110

To solve the problem, this patch proposes to alter these primary key to bigint, which is next default type of rails.

Please review this @cookpad/dev-infra cc @takonomura

[eagletmt]

Could you update spec/dummy/db/schema.rb by running the migration?

[riseshia]

Changed(rebased):

• apply migration to db/schema
  • duplicated table definition is deleted.
• Respect current migration when rollback
  • meaning to say, these 2 columns will be signed int after rollback
• add auto_increment which seem to be lacked when change_type ;)