Merge pull request #222 from myfavouritekk/pip

Add the cheat sheet for pip.

cheat/cheatsheets/pip

@@ -0,0 +1,21 @@
+# Search for packages
+pip search SomePackage
+
+# Install some packages
+pip install SomePackage
+
+# Output and install packages in a requirement file
+pip freeze > requirements.txt
+pip install -r requirements.txt
+
+# Show details of a package
+pip show SomePackage
+
+# List outdated packages
+pip list --outdated
+
+# Upgrade all outdated packages, thanks to http://stackoverflow.com/a/3452888
+pip freeze --local | grep -v '^\-e' | cut -d = -f 1 | xargs -n1 pip install -U
+
+# Install specific version of a package
+pip install -I SomePackage1==1.1.0 'SomePackage2>=1.0.4'