Support either sqlite3 or pg databases

Conflicts:
	Gemfile
Remove invalid admin tests
Remove invalid helper file for Admin::PayPalRefundsHelper
Remove 'NOT PRODUCTION READY' notice from README
Update README.md

Update gem location to point to this project.
NEMO-536 in cvoerage test autoload all ruby files (except those listed in rcov_exclude_list.rb).
Don't instantiate provider in provider_class

It was possible for payment_class to be called, which instantiated a new
`PayPal::SDK::Merchant::API` object before paypal was configured by the
code in .provider. This caused the error:

  No such file or directory - config/paypal.yml

This changes provider_class to just return the class itself. It also
overrides `.provides?` to be more explicit about the behaviour.

Fixes #15
Fixes #26

Conflicts:
	app/models/spree/gateway/pay_pal_express.rb
Convert amounts like '21,99' to '21.99' because the Big International Payment Company can't handle international amounts

Fixes #11
Fixes #30
Fix UT to use headless browser (phantomjs) so that it can be tested in Jenkins
Fix UT for better_spree_paypal_express
exclude db/**/*.rb from coverage test
update rspec setup to support headless operation, primarily for CI automation
pull unit test fix changes, based on feedback from pull request to better_spree_paypal_express. includes a couple of bug fixes from original project as well.
Add support for handling 3rd party credentials with paypal express (accelerated boarding). Added seller account email setting and updated backend to use it when available.
NEMO-1838 Merge branch '2-0-stable' into 2-2-nemo-stable

Conflicts:
	Gemfile
	README.md
	app/models/spree/gateway/pay_pal_express.rb
	spec/models/pay_pal_express_spec.rb
	spec/spec_helper.rb
NEMO-1838 Upgrade Spree
NEMO-1838 Increase spec timeout
NEMO-1838 Add byebug
NEMO-1838 WIP
NEMO-1838 temporarily bump patch level