Add .gitignore file.

.gitignore

+# editor artefacts
+*~
+.#*
+\#*#
+.*.swp
+
+#  build artefacts
+*.rej
+
+# Python build artefacts
+/build/
+/dist/
+/_venv/
+*.py[cod]
+/*.egg
+/*.egg-info
+/*.egg-link
+
+/nosetests.xml
+/.coverage
+/.tox
+/.achievements
+/.installed.cfg
+/.ropeproject
+
+# Mr Developer
+/.mr.developer.cfg
+/.project
+/.pydevproject
+
+# OS generated files
+*.DS_[sS]Store*
+ehthumbs.db
+Icon?
+Thumbs.db
+*.pid
+._.**~