Merge pull request #732 from bsipocz/MAINT_pytest_timeout

MAINT: adding the usage of pytest-timeout

Author: bsipocz

setup.cfg

@@ -7,6 +7,7 @@ doctest_plus = enabled
 text_file_format = rst
 addopts = --doctest-rst --doctest-continue-on-failure
 remote_data_strict = true
+timeout = 30
 filterwarnings =
     error
     ignore:numpy.ndarray size changed:RuntimeWarning
@@ -78,6 +79,7 @@ test =
     pytest-doctestplus>=0.13
     pytest-astropy
     requests-mock
+    pytest-timeout
 docs =
     sphinx-astropy