Add Jinja2 as a Git submodule
Add config option to disable templates
Add support for loading Jinja2 templates
Trim newline from beginning of blocks

This allows for a somewhat more readable template.
Handle input as utf-8 strings
Send default value to template
Optionally use Jinja2 templates for notification rendering

- Defaults are provided so that GitTail can be used without Jinja2.
- data dict is used to a greater extent to share template variables.
Add default Jinja2 notification templates

Template files which provides identical results to current
Jinja2-independent implementation.
For console output, indent consecutive lines based on first line's timestamp

Possibly somewhat more readable

Template-independent version is intentionally not given this feature
- Partially as a demonstation of customizability
- Partially as a hint that template-independent rendering exists
  only to provide a baseline of functionality, without ambitions
  to be feature-complete
Add config option to use a custom template path
Optionally determine custom template path from command line arguments
Split config sections
Add config options to control libnotify message properties
Add option to specify SSH user
Build argument lists prior to executing command
Add option to specify SSH port
Require bash
Do not display the commit hash in the default templates

Most of the time, a glance at the hash in a notification that disappears
within 10-15 seconds, does not tell a human anything.

For workflows where having the hash in the notification is important,
the templates can be overridden.
Reverse commit order

Sorts the commits within a single repository by time ascending
instead of by time descending, which is nicer when printing to the console.

As a side effect, the order of the repos are reversed too.
Conditionally include commit url

Avoids additional newline when url is not set