Add directed graphs to document relations between latest BF jobs

This commit is a proof of concept for the usage of the sphinx.ext.graphviz
extension. The latter extensions could allow to insert directed graphs
describing the relationships between CI jobs. Note this proposal would also
impose graphviz as a prerequisite to build the contributing documentation.
Add graphviz dependency to the Travis build
See node shape and font size
Set font size to 9
Add workflows for BIOFORMATS merge jobs
Add OMERO graphs
Add description for deploy jobs and group build jobs
Add integration jobs relationships to the directed graphs
Preserve line breaks in multi-row cells to improve readability
Add minimal information of Bio-Formats C++ jobs and fix artifactory
List breaking jobs in the continuous integration page
Add push jobs to the OMERO jobs table
Merge remote-tracking branch 'origin/develop' into bf_latest_jobs_graph

Conflicts:
	.travis.yml
Document latest Bio-Formats-5.1-merge-daily workflow
Add Bio-Formats test images good jobs
No test iamges good job for Bio-Formats 4.4
Remove unwanted links
Update relationships between Bio-Formats 5.1 merge jobs
merge develop -D org: PR 626 (Add new Squash tutorial and screenshots)
merge develop -D org: PR 683 (Add directed graphs for Bio-Formats latest jobs)