Added the option to not generate inline styles

I needed to be able to customise the text without filling a stylesheet with `!important`, so I've added options to not generate the inline styles.

I couldn't find any documentation on running your unit tests with Karma (which was failing, I think there may have been breaking changes in the Karma config file format? It's not a tool I have much experience with, sorry), but I've added a grunt task to run them with Jasmine (`grunt jasmine`). Two of the tests do seem to be failing (and were failing before I made any changes), but they're to do with the SVG output - I think that might be because Jasmine is running them with PhantomJS whereas it looks like you had Karma set up to use headless Chrome, but honestly that's just a guess.