Enable to custom triangle shape

Use $width and $height to custom triangle shape, if omit $height, this
mixin will generate code in the old way. The only downside is that
$width value should always be even number, otherwise triangle width
will be short 1px.
Enable to custom triangle shape for up-left, up-right, down-left, down-right
adding package.json
adding .npmignore
Refactored HTML5 text input addon

Avoids upcoming SASS varialbe rescoping issues.
Refactored HTML5 button input addon

Avoids upcoming SASS varialbe rescoping issues.
Adding new assign function
Used by html input types addon.
Moving function declaration to separate file functions/_assign.scss
adding MIT license to gemspec - fixes #302
Include version on bower.json

Bourbon’s version in Bower registry is still 3.1.8, which doesn’t include bower.json, thus installing files/paths that should be ignored.
Update size mixin to not accept unitless numbers

Let's just try to be explicit about this. CSS doesn't allow unitless
widths and heights, why should we? Also, there's no obvious default
one we could fall back to.
Simplify placeholder mixin
Adds font-feature-settings mixin
Accept 2-element list for `$size` and `$color`

The first value in $size would be the width value, and the second would
be the height value. The first value in `$color` would be foreground
color, and the second woud be the background color.
Merge pull request #309 from caarlos0/license-missing-gemspec

adding MIT license to gemspec - fixes #302
Merge pull request #308 from hmps/master

Refactored HTML input addon
Merge pull request #315 from mondoreale/simplified-placeholder-mixin

Simplified placeholder mixin
Add all prefixes to keyframe spec version, fixes #301

Latest versions of chrome are using the keyframe spec version but are ignoring unprefixed animations. Adding prefixed versions to spec keyframes fixes this.
Fixed deprecation warnings for sass-3.3-rc
Update to version 3.2.0.beta.2