Meta tag model creation

* Adds files to .gitignore
* Remove sqlite db
Meta tag model creation

* Change spree metatags table's fields
* Change locales for spree metatags
Meta tag model creation

* Replace validations in spree/metatag model
* Change attribute's names in spree/admin/metatags/_form partial
* Change attribute's names in spree/admin/metatags/index view
Meta tag model creation

* Remove overrides for admin/products views
* Change method in add_title_meta_tag override
Meta tag model creation

* Creates factory for metatags
* Adds specs for spree metatag model
* Adds requires for factories and shoulda matchers
Meta tag model creation

* Configure spec_helper file
* Adds feature specs for admin metatag section
* Adds feature specs for metatags in public area
Meta tag model creation

* Change logic in meta_data helper method
* Remove unnecesary scope