Add "composer/composer": "1.0.*@dev" to composer.json
Add getter function for an extension's basepath
Register an extension's Composer JSON and Bolt name in the registration
process
Let command runner find the extension's YAML configuration file
Correct a typo
Handle lowercase readme.md
Merge branch 'master' of https://github.com/bolt/bolt into feature/improved-extension-interface

Conflicts:
	app/src/Bolt/Extensions.php
Merge pull request #1655 from GawainLynch/feature/improved-extension-interface

Improved extension interface
Small additional fix for #1655