Add Linux walkthrough scripts.

This is a direct copy of the files in
https://github.com/manics/omero-install/commit/6ca41e4d77f57eaad155a4686ea68c5325a7daca
Add Linux walkthrough document referencing the walkthrough scripts
Fix typos
Use American spelling/grammar
Fix download file titles
Fix postgres startup, use full path to omero
Add note about settings.env, clarify nginx setup
Update to 5.0.2 release URL
Remove unneeded cd ~omero, add comment about commented lines
Make some system usernames bold
travis: Switch from raring to saucy

raring has been removed from the mirrors and was no longer supported
Merge pull request #871 from rleigh-dundee/travis-saucy

travis: Switch from raring to saucy
Move jvm settings to adv. configuration (See #12311)

Now that the default memory configuration need not
be modified by default, it's less critical that the
info be embedded in the main installation page. Also,
this text will need to grow substantially in order to
make the usage clear, and repeating that between unix
and windows seems error prone.

Conflicts:
	omero/sysadmins/server-advanced-configuration.txt
Formatting fixes & grammar improvements
Fix troubleshooting
Clarify 'may want to tune' section
First draft of updated docs
Add :file: markup for indexer, etc
Fix ending periods
Improve psutil/jmx paragraph