Use vim's autoload feature to reduce startup time

Without this, loading both lusty-explorer and lusty-juggler took 55ms
on my machine (see vim --startuptime), most likely due to loading the
Ruby interpreter.  With this, the combined loading time is less than
1ms.
Update test framework for autoloads
Only set colorcolumn in versions of Vim that have it

Fixes a minor bug in some Vim installations.
Updated README to show new location of generated files
Update README
Merge branch 'rosslagerwall-autoload'
Update contributors.