Updates .gitignore to allow edits to khan data channel.
Allows channel specific rebranding of logo and homepage.
Adds branding for KA Lite channel.
Adds channel data importing to contentload command.
Merge branch 'develop' into rebrand

Conflicts:
	.gitignore
Fixes up paths for channel_data.
Merge pull request #2557 from rtibbles/rebrand

Allow homepage and logo rebranding
Merge branch 'develop' into feature/2417-add-a-base-test-suite-for-ka-lite