Cleanup old API code

Drop the records code in favor of the new API code. Also remove tests
and documentation related to the old code.
Update PERMISSIONS constant

The permissions have changed upstream, this updates the PERMISSIONS
constant to match the new changes.

Related to #1507
Add NetmaskField and update Subnet entity

Due to recent upstream builds the mask Subnet's fields are being
validated for a valid netmask value. This adds a NetmaskField that
generates valid netmasks using FauxFactory gen_netmask generator. Also
updates the Subnet's mask field to NetmaskField.

Related to #1514
Merge pull request #1509 from elyezer/update-permissions-constant

Update PERMISSIONS constant
Merge pull request #1515 from elyezer/update-subnet-entity

Add NetmaskField and update Subnet entity
Merge pull request #1506 from elyezer/cleanup-old-api-code

Cleanup old API code