Add .jshintrc file

This will help maintain code consistency when accepting outside
contributions.

I made this as basic as possible to get things started.
Remove overly eager .gitignore directive

The "s*.js" line ignore *every* file in the entire project that started
with an "s".
Fix "Unreachable 'return' after 'throw'" JSHint warning
Fix "Missing semicolon" JSHint warning
Fix "Bad line breaking before '+'" JSHint error
Fix "Bad line breaking before '='" JSHint warning
Fix "'path' is already defined" JSHint warning
Fix "'params' is already defined" JSHint warning
Fix "'twauth' used out of scope" JSHint warning
Merge pull request #20 from dlindahl/issues/jshint

Add JSHint compliance