Tweaking code to find default location of the database

It turns out that this bit of code was correct, but hopefully now it's clearer.

It's still pretty confusing where this is set, and in what priority.
(eg. the .rmgrc config file). I'm not sure why the prior one seems to work in other places
Add work_in_progress decorator for currently failing Unit Tests

This is a proof (test) of concept. If it works, then we should add this
decorator to all the unit tests that we currently EXPECT to fail.
That way, the Travis-CI build test will pass - the failing tests will
just be skipped if they fail (still with an error message).

We shouldn't forget to go and fix the tests though!
Merge pull request #199 from rwest/fixtests

Progress towards fixing unit tests.  

There are some fixes to the makefile, instructions, and default database location.
Also, a work_in_progress decorator, that we should use to annotate any Unit Tests that we currently expect to fail. You just add @work_in_progress to the line before the unit test definition. 
If someone could do that for all the currently failing tests, as a half-way house to actually making them work, we will at least be able to detect changes and extra errors.
Use the https not git@ protocol to get the RMG-database in .travis.yml

The builds got this far then stopped for 10 minutes and were killed:
$ git clone git@github.com:GreenGroup/RMG-database.git
Cloning into 'RMG-database'...
The authenticity of host 'github.com (192.30.252.128)' can't be established.
RSA key fingerprint is 16:27:ac:a5:76:28:2d:36:63:1b:56:4d:eb:df:a6:48.
Are you sure you want to continue connecting (yes/no)?

Hopefully the https version can continue without the RSA fingerprint check...
Use system site_packages (and numpy/scipy) in travis config.

Currently it spends thousands of lines of log file (and quite some time)
compiling scipy for each build. The Ubuntu apt-get install of python-scipy
should save this, but you need to enable the system site packages (instead
of the isolated virtual environment) to use it. [1,2]

Hopefully this (using the system site packages) also fixes the apparent
failure of rdkit: current build failed with:
echo "Checking you have rdkit..."
Checking you have rdkit...
Traceback (most recent call last):
  File "<string>", line 1, in <module>
ImportError: No module named rdkit

[1] http://danielnouri.org/notes/2012/11/23/use-apt-get-to-install-python-dependencies-for-travis-ci/
[2] https://github.com/dnouri/nolearn/blob/master/.travis.yml
Simplify travis config: no QM and no Python 2.6

Trying to get the simplest possible configuration working first,
then will add complexity.
Remove redundant parts from Travis config file.

--use-mirrors has been deprecated, and pip install .  likely isn't needed
Try using the apt-get version of matplotlib too, in travis build.

This should speed up and simplify the build, if it works.
Try building RDKit from source during Travis-CI testing

These lines in the build script are based off the RDKit travis config
https://github.com/rdkit/rdkit/blob/master/.travis.yml
But modified to turn on InChI support
Once this is working we can worry about cacheing the finished
build to speed it up.
Travis gets and builds PyDAS and PyDQED

Unlike the instructions for users in our installation guide,
don't have Travis sudo the make install for PyDAS and PyDQED.
'sudo' on Ubuntu makes it discover the wrong python, which then doesn't
have Cython installed, and it all goes wrong. Hopefully this clears it up.
I also split into several lines, to make debugging the Travis log easier.
Trying to get Travis things in the right directories.

 - RMG-database
 - RPyDAS
 - RPyDQED
 - Rrdkit
etc.
should all live alongside, not inside, the RMG-Py directory.
Hopefully this works solves the database problem
Try running eg1 as well as make test in travis testing.