Add `id` attribute to woocommerce_form_field args

This change allows developers to supply their own id attribute
when using the `woocommerce_form_field` template function.
The default ID is the escaped key, keeping the default behaviour.
Revise id, input_class and label_class escaping
Merge pull request #6208 from ragulka/form-field-id

Add `id` attribute to woocommerce_form_field args
JS min
wooconf plug on welcome screen.
Removing RC1 from version.
2.2 .pot file
Only display WooConf banner if WooConf hasn't happend yet.
Merge branch 'master' of github.com:woothemes/woocommerce
Fixed a small typo.
Display a backgroud color so text is readable while image loads.
fixed the order items qty calculation, closes #6209
exclude api dir from docgen
updated for WC 2.2
Added release date to changelog
Merge branch 'master' of github.com:woothemes/woocommerce
prevented errors in the installation caused by old plugins
Stop old plugins breaking installer read me

= 2.2.1 - 10/09/2014 =
* Fix - Small tweak to the installer to prevent errors caused by
outdated plugins.
* Tweak - Small tweak to update notification to remind users to update
old plugins prior to install.
fixed the mijireh plugin slug
updated the readme.txt