travis: Test also builds with pypy.
travis: Allow tests with pypy to fail.

Since people usually think of PyPy as a second-class citizen, we don't fail
in case one of our modules barfs with PyPy, but it is certainly a good thing
to test with it (and this author here would love to see PyPy become more
respected as it has the potential to make Python a high performance
language).
travis: Make nose tests verbose.

This way, we can easily see what works by names, instead of only seeing
little dots.
Update Python requirements in documentation.
Add required package six to the list of packages, as well as update instructions for requests package for Mac. In addition, add details on selecting python 2.7 for Mac Ports in order to get coursera-dl to find the required python libraries.
More informative error messages

I also think it should look up for the host coursera.org instead of
'coursera-dl'.
Merge pull request #176 from untitaker/master

Make some error messages wrt authentication more informative.
Add newline to the last line of file.
Merge pull request #177 from rdcastro/master

Update documentation of prerequistes for OS-specific installations.
README: Add warning about installation method of dependencies.
README: Try to fix markup.

[skip ci]
coursera: coursera_dl: Add tests for minimum versions of some modules.

We keep getting bug reports unrelated to our code. This addresses, in part,
issue #139, but there is more to come to fix that bug.
coursera: Fix test breakage with missing imported module.
coursera: Fix test breakage with missing imported module, take 2.

I am sleep deprived and should not be allowed anywhere near a computer that
doesn't have nosetests available, for the public good.
README: Add note about trying to download materials from old courses.

[ci skip]
Fix authentication

Coursera changed the authentication url to
https://accounts.coursera.org/api/v1/login and replaced the login and
session cookie with a CAUTH cookie.
Merge pull request #181 from jonasdt/auth

Merge changes from Jonas to adapt to changes in Coursera's login scheme.

Kudos to Jonas, as usual.
move cache folder from ROOT/_cache to tempdir determined by tempfile module

Signed-off-by: Dominik Richter <dominik.richter@gmail.com>
create a subfolder in the temp directory for coursera-dl

use the style inspired by: https://github.com/jplehmann/coursera/pull/183/files

Signed-off-by: Dominik Richter <dominik.richter@gmail.com>
Merge pull request #188 from arlimus/master

Change the location of the cache directory to not be put on the location of
the executable pieces, as that prevents users from installing coursera-dl in
a system-wide fashion.

Instead, use the appropriate system facilities to create temporary files, as
per the `tempfile` module.

This is the result of a cross-polination of fertile discussions among
@jonasdt, @arlimus, and @euyuil.

This closes #183 and #188.


Signed-off-by: Rogério Theodoro de Brito <rbrito@ime.usp.br>