Introduce basic theming system
Rename `variables.less` => `themes.less`
Pull colours into themes.less
Pull a few common things into mixins
Consolidate some colour styles
Give stripe elements more generic classnames
JIRA colours
Move images into github subdirectory
Add jira theme images
Implement JIRA theme
Replace remaining GH reference in template
Update README with backend information
Add contributors to README
Merge pull request #16 from 99designs/jira-theme

Import jirasurvivor theme