TS-70 Fix nosetests

[wschoenell]

Travis is returning errors on these tests.
#15 chimera.core.tests.test_config.TestConfig.test_position ... FAIL
#50 Failure: ImportError (No module named asciidata) ... ERROR
#51 Failure: ImportError (No module named asciidata) ... ERROR
#52 chimera.util.tests.test_ds9.TestDS9.test_basics ... application-specific initialization failed: no display name and no $DISPLAY environment variable

Unable to initialize window system.
ERROR
#53 chimera.util.tests.test_ds9.TestDS9.test_use_global_ds9 ... application-specific initialization failed: no display name and no $DISPLAY environment variable

Unable to initialize window system.
FAIL

https://travis-ci.org/astroufsc/chimera/builds/37303505

[wschoenell]

The first one:
https://github.com/astroufsc/chimera/blob/master/src/chimera/core/tests/test_config.py#L179

2nd and 3rd are due to chimera's dependency to the very old module asciidata:
http://www.stecf.org/software/PYTHONtools/astroasciidata/

4th and 5th are due to the intent of opening DS9 on the travis. Can be fixed as follows:
http://docs.travis-ci.com/user/gui-and-headless-browsers/#Using-xvfb-to-Run-Tests-That-Require-GUI-(e.g.-a-Web-browser)

[phsilva]

Fixed.