deliteful/Select initial version

This pull request implements https://github.com/ibm-js/deliteful/issues/111 (the issue contains some design information).

Accessibility tests done (found no issue):
* VoiceOver on iPhone iOS 7.1.
* Keyboard accessibility on latest Chrome/FF/IE10 on Win7.
* High Contrast on latest FF and IE10 on Win7.

Accessibility tests NOT yet done (will be done soon):
* Jaws

**Update**: test with Jaws (latest version, v. 15) now done (on Win7). Behavior seems OK with FF 30 and IE10. Differently, with Chrome 35, it does not announce the selected option (although it correctly announces the option initially selected)..

Bidi: not yet considered.

Sample: I will add a basic one, but in the longer run there should be a unique sample for the form controls and the Select will be show-cased there. For now, tests/functional/Select.html can be used for seeing the widget in action.

Known issues:
* Some coding/design points are under discussion and/or marked with TODO in the code.
* Some rendering issues exist due to browser bugs such as:
  * Chrome/Win
    * https://code.google.com/p/chromium/issues/detail?id=4579
    * https://bugs.webkit.org/show_bug.cgi?id=28900
    * Wrong width (truncated label due to scrollbar - but truncation avoided thanks to the padding used in Select's themes)
    * Template binding works bidirectionally in all browsers for all properties except in Chrome 35/Win7 for the size property. (Will try to isolate a reduced test case.) (Update: same trouble on Mac OS X with Chrome 35 and Safari 7, while OK with FF 30). Update: entered https://github.com/ibm-js/delite/issues/205 for this issue.
  * Chrome and FF / Win
    * Unneeded scrollbars (FF and Chrome/Win7, but not IE10/Win7...)
  * FF/Win
    * Slightly wrong height for multi-select because of the padding (ok on Chrome and IE10). Workaround available for users: apply style to remove the padding.
  * iOS 7.0.x broken with multi-select (luckily, fixed in iOS 7.1)
    * http://stackoverflow.com/questions/20039194/multiple-select-in-safari-ios-7
    * https://discussions.apple.com/message/23745665#23745665
    * https://discussions.apple.com/message/23607781#23607781
    * https://discussions.apple.com/thread/5563234

Remark: for now the ios and holo themes (which are low priority) are identical to the bootstrap theme.

Next steps:
* (of course) process feedback. Update: done.
* Further test cases. Update: some additions done; more to come.
* Quick basic sample (awaiting for a global form controls sample). Update: done.
* More API doc improvements and user guide.