Ntfy

Unified config/options

All config options can now be configured via the CLI `-o` flag and vis-versa.

Included Pushover Application Token

`ntfy` now includes an application token for Pushover so it is now an optional config parameter.

- also makes config argument optional for backends that don't require it (desktop backends)

Also:
- Call signatures of `notify()` methods cleaned up
- Generic way of passing options specific to backends

Linux notifications switched to use dbus and windows pulls in pywin32 by using pypiwin32 on pypi.

Switched to RST so that PyPi looks prettier: https://pypi.python.org/pypi/ntfy