Add pytest 'data_download' mark

Exclude tests that need datafiles from tox, since
travis doesn't support ftp.

setup.cfg

@@ -7,3 +7,4 @@ markers =
     no_external_software_required: test can be run without external detectors
     notfixed: known failing tests
     slow: slow tests
+    data_download: Requires downloading data values

tox.ini

@@ -19,5 +19,6 @@ commands = flake8 tral/
 deps =
     -r{toxinidir}/requirements_dev.txt
 
+# For now, only run travis-compatible tests
 commands =
-    pytest -m no_external_software_required
+    pytest -m no_external_software_required -m "not data_download"

tral/repeat/test/repeat_test.py

@@ -19,6 +19,7 @@ def test_standardize_amino_acids():
     assert repeat.standardize("ABDEF-G", "AA") == "ADDEF-G"
 
 
+@pytest.mark.data_download  # needs data/pvalue/AA/phylo_gap01/3_2.npz
 @pytest.mark.no_external_software_required
 def test_repeat_ambiguous():
 

tral/sequence/test/sequence_test.py

@@ -73,7 +73,7 @@ def test_detect_repeats_with_repeat():
     assert test_optimized_repeat.repeats[0].msa == TEST_RESULT_REPEAT_MSA_SINGLE
 
 
-@pytest.mark.no_external_software_required
+# Requires hmmbuild
 def test_too_big_hmms():
 
     test_repeat = repeat.Repeat(msa=TEST_RESULT_REPEAT_MSA_LONG)

tral/test/test_paths.py

@@ -27,7 +27,7 @@ def test_package_config(config_dir):
     with pytest.raises(FileNotFoundError):
         ini_file = paths.config_file('foo', config_dir=config_dir, config_url=DISABLED_URL)
 
-
+@pytest.mark.data_download
 @pytest.mark.no_external_software_required
 def test_download_config(config_dir):
     small_file = ["data",