Configure Travis continuous integration

Create a continuous integration script for Travis-CI that installs all
system and pip dependencies, configures CATMAID according to the
published documentation, initializes and migrates the database, starts
the default server, and runs the camaid.tests suite. Travis is not yet
enabled for acardona/CATMAID, but this allows for easy testing in forks.

Also create an explicit, correct package dependency list for Ubuntu
12.04 used when setting up the Travis instance. Lists of dependencies
are duplicated elsewhere and frequently have incorrect package names or
fall out of date. Going forward, these redundant lists should be removed
and reference a single canonical list of package dependencies for each
OS/repository.
Tests: remove dependence on PostgreSQL sequence

Because of unreset sequences, this test was failing on Travis even
though the intent (retrievable Project id) was successful.