RTL fix extra space in front of severity on Edge, Firefox

The fix in #49 caused one issue on Edge because Edge does not recognize :host-context, so an extra space appeared in front of severity on Edge when dir is LTR.

Since Firefox does not support :host-context either, it still shows extra right space on Firefox when dir is RTL

RTL: Extra white bar appears on notice message under RTL

RTL: Extra white bar appears on notice message under RTL

Corrected behavior of alert message when expanded property is set

v1.3.4

Merge pull request #45 from predixdesignsystem/41-correct-expanded-pr…

Polymer 1.x/2.x hybrid element support

v1.2.0

Polymer 1.x/2.x hybrid element support

Design Refresh

• The look and feel has been updated as part of the design refresh, especially regarding the display of the alert severity icons. Code for the various icon shapes has been moved to px-alert-label for reusability.
• No API breaking changes.

v0.6.6

Merge branch 'master' of https://github.com/PredixDev/px-alert-message

Upgrade to Polymer 1.5.0

v0.6.0

travis badge + downgrade FF tests

Fire event when dismissing message

v0.4.0

fix history

API Docs and minor Sass update

added comments for api documentation and replaced @extend with @mixin in sass/px-alert-message-predix.scss

updated README, replacing docs with auto-built ones from gh-pages.

v0.3.3

updated README, replacing docs with auto-built ones from gh-pages.