Just use setup.py

(don't keep a second copy in `requirements.txt`)

.gitignore

@@ -33,3 +33,7 @@ obj
 *.pyproj
 *.sln
 *.suo
+
+# virtaulenv
+env/
+env*/

requirements.txt

@@ -1,7 +0,0 @@
-parsedatetime >= 1.2
-pytz >= 2013b
-pycrypto >= 2.6
-argparse==1.2.1
-tzlocal >= 1.0
-keyring==3.0.5
-python-dateutil==2.2

setup.py

@@ -72,7 +72,7 @@ setup(
     install_requires = [
         "parsedatetime>=1.2",
         "pytz>=2013b",
-        "tzlocal==1.0",
+        "tzlocal>=1.0",
         "keyring>=3.3",
         "python-dateutil>=2.2"
         ] + [p for p, cond in conditional_dependencies.items() if cond],