Refactor javascript into multiple files

First step
snowpak.sh: accept yui path from env variable
Whitespace
Refactor into multiple files: first step done
Generate new sp.js
Add content type to async example html
Remove some this references
Generate sp.js
Non-coding tidy-up, including:
 - Standardise all files on tabs not spaces
 - Two empty lines at end of each file
 - Remove unnecessary comments at end of JSON file
 - Standardise on one blank line between functions
 - Remove <SNOWPLOW STARTS> / <SNOWPLOW ENDS> comments
Re-added line break to end of dependencies file and re-minimized
Took the first cat out of combine_files()
Merge pull request #1 from alexanderdean/feature/refactor_javascript

Tidy-up (predominantly whitespace)
Readd memoization of SnowPlow module
Generate sp.js
Set content type for html page in sync
Fix synchronous mode

Synchronous methods weren't exported
Generate sp.js
Manual 'merge' of @mtibben's #67 pull request
Adding in license files
Stubbed the README