Refine version requirements with upper bounds

requirements.txt

@@ -1,14 +1,14 @@
-usgs>=0.1.9
-requests>=2.7.0
-python-dateutil>=2.5.1
-numpy>=1.10.4
-termcolor>=1.1.0
-rasterio>=0.32.0,<1*
-six>=1.8.0
-scipy>=0.17.0
-scikit-image>=0.12.3
-homura>=0.1.3
-boto>=2.39.0
-polyline>=1.3
-geocoder>=1.9.0
-matplotlib>=1.5.1
+usgs>=0.1.9,<1.*
+requests~=2.7
+python-dateutil>=2.5.1,<3.*
+numpy>=1.10.4,<2.*
+termcolor~=1.1
+rasterio~=0.32
+six~=1.8
+scipy~=0.17
+scikit-image>=0.12.3,<1.*
+homura>=0.1.3,<1.*
+boto~=2.39
+polyline~=1.3
+geocoder~=1.9
+matplotlib>=1.5.1,<2.*