Fix RFC822 filters + More tests (#257)

* Make rfc822 filters compatible with Windows systems.

.strftime() is relative to the system it's being run on.
UNIX has '%s' for seconds since the EPOCH, Windows doesn't (ValueError).
Solution: use .timestamp() to achieve the same result on both platforms.
This also allows us to drop the float() around it, since it returns a float.

* Start testing filters

* Add placeholders for more tests

* Make 'tests' folder a Python package

Now you can run tests with just `pytest tests`

* Update readme and travis config

* Test timesince()

* Update and organize .gitignore

Deleted: (nothing)
Added: Coverage files, .idea\

* Test filter_truthy, category_name

* Tests for backend.py

* Tests for bencode.py

* Move (empty) test_models.py to tests package

* Tests for utils.py

* Fixes for flattenDict

* Change name to `flatten_dict`
* `newkey` was assigned but never used

* Add a helper class for testing

* Show coverage on Travis

(only Travis for now...)

* Remove IDE

* Use correct assert functions

* Update README.md

.gitignore

@@ -1,12 +1,29 @@
-*.sql
-/.vscode
-/venv
-*.swp
+# Cache
 __pycache__
 /nyaa/static/.webassets-cache
+
+# Virtual Environments
+/venv
+
+# Coverage
+.coverage
+/htmlcov
+
+# Editors
+/.vscode
+
+# Databases
+*.sql
 test.db
-install/*
+
+# Webserver
 uwsgi.sock
-/test_torrent_batch
+
+# Application
+install/*
 config.py
+/test_torrent_batch
 torrents
+
+# Other
+*.swp