Add introduction, change workflow and move model.
github help links https -> http to fix build
Merge pull request #459 from hflynn/rebased/develop/githelp

Github help links (rebased onto develop)
Merge pull request #457 from sbesson/rebased/develop/homebrew_default_ice

Update Homebrew installation page to expose Ice 3.4 as the default version (rebased onto develop)
merge develop -D org -I include -E exclude: PR 369 (Cpp: Correct content and markup)
merge develop -D org -I include -E exclude: PR 437 (Generate PDF using XeLaTeX)
merge develop -D org -I include -E exclude: PR 448 (Managed repository)
merge develop -D org -I include -E exclude: PR 450 (omero: Python 2.6 is the minimum supported version)