Revert "Remove optimistic lock from inventory units."

This reverts commit 531688404d29f64a81c254262670877e1e9ff3cc.
Fix password fields being visible, test Twitter authentication

Conflicts:
	app/views/spree/shared/_user_form.html.erb
added path_prefix preference

Fixes #93
Yaml lint locales.
Refactor for Spree 2.0.

- Cleanup and code formatting.
- 1.9 hash syntax.
- Build statuses.
- Simplecov, coveralls and gemnasium.
- Locale tests.
Travis config.
Minor BSD changes.
Add Swedish locale.
Fix for Travis and use Spree 2.1.0.beta
Cleanup readme.
Add filters to simplecov.
Fix locales for Spree namespace.

Also add some untranslated keys and fix keys with wrong key names.
Update Travis to test 2-0-stable branch also.
Fix broken links and better contribution info.
Use same branch for Spree 2

- Correct BSD version
- Swap to webkit
- Integrated version style
Some specs that need to be done.
Bump away beta.
Require authorization_helpers
Add guard for spec runs.
Remove Versionfile.