Injecting CSS font styles into `<head>` using additional param data

- spreadsheet.js updated
	- using `getFontCssStyle` from widget common utils to return a string representing a CSS class containing appropriate font styles
	- `additionalParams` function logic added for checking `name` and `value` and creating and injecting the style node into the `<head>` of the document
Merge pull request #35 from stulees/master

Injecting CSS font styles into `<head>` using additional param data