[datatype-number] Fix regression in number parsing

A change introduced the use of `parseFloat` which returns numbers for
strings like `'1a'`. Revert this change but maintain the special case it
was meant to fix (`+'   ' === 0`). See
https://github.com/yui/yui3/commit/9e431fa1eeee94919cea1a28099b383d11b4ae18
[datatype-number] Test string+number edge cases
[datatype-number] Add tests for booleans
[datatype-number] Fix boolean edge cases
Merge remote-tracking branch 'juandopazo/number-parse' into release-3.14.0
datatype-number: Build
datatype-number: Update HISTORY.md