Add an install command

Upgrade* classes renamed Install*
Add a parameter and conditional to control whether an upgrade or new install is performed

Separate --upgradedb (upgrade) or --initdb (new) params for database
Maintains backwards compatibility for now, will probably change to a common argument when the command line args are refactored
Fix test_upgrade.py (UnixUpgrade->UnixInstall)
If Stop caught with non-zero code, print "ERROR:"
Add help text for --initdb and --upgradedb
Change .travis.yml to run separate install and upgrade tests
Check for symlink before downloading

Also rearrange log messages
Merge pull request #36 from manics/server_init

omego install