PayPal: Add MassPay to recipients by UserID

MassPay allows payment to recipients by EmailAddress, UserID or
PhoneNumber; EmailAddress is the default, and this adds support for
UserID.

https://developer.paypal.com/webapps/developer/docs/classic/api/merchant/MassPay_API_Operation_SOAP/

Closes #693.
Authorize.Net: Add authorization_code to response

This makes the issuer 6-digit 'authorization code' to accessible in
Response#params.

Closes #686.
Make Rails 4 a supported version

Closes #687.
CyberSource: Add pinless debit card support

Closes #691.
Verkkomaksut: Add item title field

Item title is visible in payment widget and gateway admin interface.

Closes #700.
PayJunction: Fix remote test

Needed a new/updated verification value.

Closes #701.
Add MerchantWare V4 gateway

http://merchantwarehouse.com/merchantware

Closes #696.
Eway Rapid: Add #store method

Closes #707.
Can't send a blank state for Skipjack
Get the test working properly
Barclays ePDQ Extra Plus: Use correct PROD url
HiTrust: Update test & live urls

Closes #753.
Merge pull request #741 from Shopify/skipjack-missing-state-fix

Can't send a blank state for Skipjack
Removes rubies that have been end of life'd

Ruby 1.8.7 - http://www.ruby-lang.org/en/news/2013/06/30/we-retire-1-8-7/
REE - http://blog.phusion.nl/2012/02/21/ruby-enterprise-edition-1-8-7-2012-02-released-end-of-life-imminent/

Rubinius doesn't say anything, but whatever, let's remove all 1.8
support.

Also moves the CI and Code Climate details to the top of the readme
Changed the error messages. According to google translate, they are equivalent :)  Also adding 'debugger' to the Gemfile.
Barclays Extra+: Remote test with minimal info

This tests that transactions with the bare minimum of required info
still succeed.
NAB Transact: Add auth & capture support

Closes #762.
Mercury: Support card-less capture and refund

Mercury is first a POS system, and only second does online transactions.
Due to this, the standard "get back an authorization you can use to do
future operations on this transaction" flow must be explicitly enabled.

This enables that flow by having Mercury return a "OneTime" token for
every #authorize and #purchase which is stored in the authorization
string and can then be used to do captures and refunds. This also adds
the amount to the authorization string so that a capture can be run
without having to re-specify the amount.

This type of "one-time tokenization" is now the default for Mercury
since it matches so much better with expected ActiveMerchant semantics.
If the old behavior is desired, pass `tokenization: false` in the
options hash when creating the gateway.
Removed 'debugger' from gem - CI is failing due to an earlier version of Ruby (1.8.7 incompatible with debugger 1.6.1)
Merge pull request #763 from Shopify/webpay_remote_tests

Changed the error messages.