add autocomplets for directives and variables

merged from atom-angularjs package
add snippets for html and javascript

merged from atom-angularjs package
merge snippets

remove some of old snipptes.
because when prefixes are duplicated, only last one works
and prefixes started with special characters, such like
`|`, `$`, doesn't work in Atom.
enhanced README
Merge pull request #3 from outsideris/merge-atom-angularjs

Merge atom-angularjs