Fixed deprecation warning for Minitest test suites
New IP address class in preparation for conversion to Postgres

The PostgreSQL ActiveRecord driver can handle the `inet` and `cidr`
types that Postgres supports, but it converts them to Ruby IPAddr
objects. In the past, we've been extending the IPAddr (and more recently
the IPAddress) class with some custom methods of our own. To support
Postgres fully, I'm now monkey-patching Ruby's IPAddr class when ANTFARM
is loaded.

This commit also includes a test case for the monkey-patching.
Using `ipaddr` instead if `ipaddress_ext` in the Initializer
Use `postgresql` as adapter name instead of `postgres`

If not, ActiveRecord won't correctly use the `pg` gem.
Ignore the `.bundle` and `vendor` directories created by Bundler
Using Postgres-native types for IP addresses, IP networks, and MACs

Modified the schema for l3_nets to use `cidr` for `address`, l3_ifs to
use `inet` for `address`, and eth_ifs to use `macaddr` for `address`.
Updated gemspec to use latest versions of ActiveRecord and pg gems

ActiveRecord 3 didn't support Postgres-native inet, cidr, and macaddr
types.
Updated regex for MAC validation in eth_ifs

The upgrade to ActiveRecord 4 identified this as an issue
Moved some tests so they don't get run for now
Got rid of the 'private_net' model
Moved execute_with_* to base Antfarm class
Adding default certainty_factor support to Antfarm config
Fixing a couple of subtle bugs in my IPAddr monkey patch
No longer requiring certain relations and tables in schema
Added a TODO in bin/antfarm
Lots of changes to get tests to pass... still not all passing yet :(
Going back to the basics with IPAddr...

Since ActiveRecord relies heavily on IPAddr when working with inet and
cidr types in PostgreSQL, me monkey patching IPAddr too much was causing
trouble. Instead, I've only monkey patched it enough to add `loopback?`
and `prefix[=]` methods to support ANTFARM code (in lieu of overriding
the constructor). Then, in the model code I just make sure the `IPIf`
class doesn't use a network string to initialize IPAddr (since IPAddr
loses all sense of the IP address if a netmask is also provided).
Changes to IPNet to account for changes to IPAddr monkey patch
Changes to IPIf to account for changes to IPAddr monkey patch
Added method to EthIf to create a L2If on creation