Error handling and timer

• Improve error handling when tasks are missing
• Using timer.infinity to keep eye_drops running
• Upgrade dependencies

Run on start

Run tasks when EyeDrops starts up.

Upgrade elixir 1.2.3

Merge pull request #5 from rkotze/elixir-upgrade-1-2-3

Elixir upgrade 1 2 3

Run tasks

When eye_drops has started you can run individual tasks or all.
Useful if you have been away for a while or had a context change and can't remember the current state of your work.

Little tidy

Remove test files from lib in published package.
Updated tests to reflect changes.
Updated readme.

First public release

Has an include_tasks switch to select configured tasks to watch.