v0.3 theme still uses old v0.2 style logos in some assets

[chris48s]

e.g:

• https://github.com/DemocracyClub/dc_base_theme/blob/master/dc_theme/static/dc_theme/images/logo-large.png
• https://github.com/DemocracyClub/dc_base_theme/blob/master/dc_theme/static/dc_theme/images/logo.png

[chris48s]

Attempted to do something about this but the logos I found in in https://drive.google.com/drive/folders/0B6Qqb1WGnb7Wb01zNE9qWE04dmc don't quite match the ones we're using in 0.3 (the tick is differently positioned on the background). Need correct assets to sort this

[symroe]

Fairly sure #29 fixes this.