Organise image folder hierarchy and change img references

[lunarias]

Images are scattered throughout the img folder and need to be placed in the proper folders. The folder hierarchy should look as follows (example):

.
img
├── acpc
    └── 2015
         └── poster.png
    └── 2016
    └── ...
├── ccpc
    └── 2015
         └── poster.png
    └── 2016
    └── ...
├── logos
├── misc

• Each contest year will be a separate folder in both acpc and ccpc.
• The names of all posters should be changed to poster.[file extension].
• All banners should also be changed to banner.[file extension]
• misc folder will have any images that don't belong in acpc, ccpc, or logos

Important: You'll have to change image references across all files in the repository once you re-organize their structure and change their name.