[IMP] base: better evaluation context on menu

Allow more complex evaluations (e.g. using time) in domain of ir.ui.menu.
Move _get_eval_context to ir.actions.actions for basic context elements.
opw 603382
[IMP] web: better content-type for attachments

Add the corresponding content type document instead the default content type.
This allows browser to detect the type of file being downloaded.
Fixes #1225
[IMP] point_of_sale: make the floor plan background fit the floor
[IMP][website_mail] improved template designer, added support for background color, font color and bootstrap buttons(inline css) in mail designer,removed other snippet, changed snippet according to new format,added theme selector in mail_designer, lodeded snippets dynamically based on theme, added font-awesome support in mail snippets, added one controller which convert font-awesome to icon

[IMP][website_mail] changed less colorpicker to inline ckeditor color picker

[IMP][website_mail] Improved discount coupon and image text snippets