switch gemspec and test fixture Gemfile to Rails 4
fix Rails4/Bundler binary stubs conflict

Rails 4 doesn't like the stubs that Bundler generates when you run
"bundle binstubs" and it crashes with a message like:

 Looks like your app's ./bin/rails is a stub that was generated by Bundler.

It appears that we weren't using the stubs anyway, so I removed the
binstubs invocation, but if we need them the new syntax to generate
Rails4-compatible stubs is "bundle binstubs rails".  You can add other
stubs after rails if you need them.
be more discriminating about which tables we try to update

The ChangeKeysToBigInt migration tries to update the tables belonging
to all of the subclasses of ActiveRecord::Base, but in Rails4 that set
includes schema_migrations which has a blank primary_key field which
causes problems like:

       PG::SyntaxError: ERROR:  zero-length delimited identifier at or near """"
       LINE 1: ALTER TABLE "schema_migrations" ALTER COLUMN "" TYPE bigint

or

       Mysql2::Error: Unknown column '' in 'schema_migrations': ALTER TABLE `schema_migrations` MODIFY COLUMN `` bigint(20) DEFAULT NULL auto_increment

To avoid this we now check that the table exists and that its
primary_key field is not blank.
fix spec ArgumentError

The signature of the ActiveRecord::ConnectionAdapters::TableDefinition
class changed between Rails3 and Rails4: it used to take one
parameter, and now it takes 4.  This is my best guess at a no-op set
of parameters, and it seems to work.
fixes to the code that resets connection adapters between tests

The postgresql adapter now defines a constant in
ActiveRecord::ConnectionHandling so we need to clean that up...

     .rvm/gems/ruby-1.9.3-p392/gems/activerecord-4.0.0/lib/active_record/connection_adapters/postgresql_adapter.rb:20: warning: already initialized constant VALID_CONN_PARAMS

...and it depends on a constant that's defined in a different file
than the adapter, so we need to include that as well.

     NameError:
       uninitialized constant ActiveRecord::ConnectionAdapters::PostgreSQLAdapter::ReferentialIntegrity
clarify code that checks if a table should be upgraded to 64bits

We need to check that the table exists and that it has a primary key.
Now both of those checks are "positive" checks so it's easier for
humans to read.  Before, one of the checks was positive and one was
negative so it was confusing.
update the readme to reflect that we're compatible with 4.0
handle "belongs_to" in migrations

"belongs_to" is equivalent to "references" in migrations.
Merge branch 'master' into rails4

Conflicts:
	Readme.md
	spec/fixtures/Gemfile
remove --debugger flag from .rspec

Looks like newer versions of rspec (3.0.0.beta1) don't support
--debugger:

$ rspec
invalid option: --debugger

Please use --help for a listing of valid options
update rspec syntax to be 3.0-compatible

In 2.x you could say expect(asdlfkd).to be_true even if the argument to
expect was true.  In 3.0 you get:

  1) BigintPk::Generators::InstallGenerator creates a bigint_pk initializer
     Failure/Error: expect( File.exists? "#{RailsDir}/config/initializers/bigint_pk.rb").to be_true
     NoMethodError:
       undefined method `true?' for true:TrueClass
     # ./spec/integration/generator_spec.rb:13:in `block (2 levels) in <top (required)>'
loosen the rails requirements in the gemspec

We'd like to work with 4.1 so we're going to change from ~>4.0 to
>=4.0.  Works on my machine.
Merge pull request #2 from caboteria/rails4

Rails4 fixes