Full RTL support

[hishamco]

RTL means Right-To-Left and is for users who use a different alphabet, which is read & written from another direction. For example: Arabic, Hebrew, Persian .. etc

FYI I already started #557

[thiennn]

I don't know what should be done to support RTL

[hishamco]

• Ability to set the language direction (either manually or automatically)
• Tweak the current themes to make them work fine for both LTR & RTL or add a new theme to prove that RTL is fully supported in SimplCommerce
• Add RTL culture
• Translate the content, resources so it's fully read & write from another direction

IMHO we did a great progress in some points, but we need accomplish some of the remaining tasks to finish this up