Fix tag closing in `addImportToFile`

Used to generate `<new-element><new-element/>` instead of `<new-element></new-element>`.
README: adding intro, updating installation, getting started, adding note about builds
README: add list of features
Fixes #4 - issues with camel casing where unnecessary
README: expanding tutorial
README: further updates to tutorial
Further changes to screenshots
Adding preview for panel + button
Bumping version
minor tweak to readme
Adding small notes section
Improve clarity in language for importing other elements
Updating to latest lifecycle events supported by Polymer
Fixing custom element sub-generator, adding docs for sub-generators
adding logo
Bumping version
Removing mention of the custom elements sub-generator until it comes back to a usable state spec wise
Typo
Merge pull request #5 from wibblymat/patch-1

Typo
Adds preview, removes coffee mention from readme