Added pathToTmp to options, creating and destroying tmp folder at start and end
got pdf.js to use tmp folder rather than cache
Added debug

- added option for debug in command line
- added option defaults in options
- added creating of debug folder in main module
- renamed caching-related methods in book.js to debug
removed all traces of cache
Removed test that essentially depended on the cache to work

test coverage will be updated further down the line
Merge branch 'remove-caching'. Closes #4.