Separate tests into folders.

Build in a matrix?

tests/examples/test_example_linear.py

@@ -0,0 +1,13 @@
+import unittest
+import sys
+from SimPEG.Examples import Linear
+import numpy as np
+
+class TestLinear(unittest.TestCase):
+
+    def test_running(self):
+        Linear.run(100, plotIt=False)
+        self.assertTrue(True)
+
+if __name__ == '__main__':
+    unittest.main()