[mubtihub] Add installation instructions for ubuntu 12.04

Conflicts:

	manuals/enterprise-api/multi-site-queries.markdown
Merge pull request #72 from awsiv/master

[multihub] Installation instructions for debian packages
Formatting
Merge pull request #73 from tzz/master

DC API docs and DC walkthrough (first section of the manual)
Minor editing of titles etc.
Remove soft linebreaks.

Need to Fix linebreaking in codeblocks via css.
Merge pull request #74 from tzz/master

minor DC doc fixes
first draft of cleaned updgrade.markdown
Merge pull request #75 from McAtte/master

First draft of revised installation.markdown
manuals/design-center.markdown: minor fixes