Autocomplete enhancements

updated the autocomplete handler to scan all lines but the current cursor position for user roles
autocomplete now filters via incremental search
added a new snipet (ast) - as the {role} ...
reasons can now be separated via "because" as well as "so that"

Autocomplete support

This release sees atom autocomplete support for ROLE definitions in a user story file

initial version

this is the initial version of the language-story atom extension