Improve props handling - respect defined types

Improve props handling - respect defined types. Current behaviour is preserved until property type (https://vuejs.org/v2/guide/components-props.html#Prop-Validation) is used.

Thanks to it you can now freely handle passing string/numbers etc. without automatic conversion and it's guessing.

Thanks @auzmartist for a PR!

Add beforeCreateVueInstance hook

Add 'beforeCreateVueInstance' hook so root component definition could be changed. Thanks @suil for PR

Typescript improvements & minor dependencies bump

• Typescript improvements (#83)
• bump document-register-element to avoid NPM errors in Windows

Typescript changes

Merging @isaaclyman PR (#82) in response to #75 comments

Improve dependency installing and bump dependencies

• Improve dependency installing, thanks @IParthJoshi (#81). Now you can npm install vue-custom-element --production without installing any dependency
• bump dependencies, e.g. demo polyfill

TypeScript completition & enable passing string values to props for creating component in the plain JavaScript.

• #75, thanks @isaaclyman
• #76, thanks @suil

Improve automatic number prop type conversion (#64)

Improve automatic number prop type conversion (#64). It shouldn't break existing apps. Thanks @alinnert!

Fix #68 (Before create hook)

Fix #68 (Before create hook), thanks @ideafm

Add .prop v-bind support to vue-custom-element

Add .prop v-bind support to vue-custom-element #66. Thanks @auzmartist!

Comment node error

Fixed #63 - HTML comments cause TypeError, thanks @jcupps