Fixed composer.json

I tried using https://github.com/themattharris/tmhOAuth.git with `composer`, by adding
````
{
	"type": "vcs",
	"url": "git://github.com/themattharris/tmhOAuth.git"
},
"require": {
	"themattharris/tmhOAuth": "master" (or "dev-master")
}
````
to my app's `composer.json` and ran `composer install`, but it always pulled the 0.7.2-devel branch, and not the master.

I then tried
````
"require": {
	"themattharris/tmhOAuth": "0.7.2"
}
````
but for some reason `composer` fails to even process the entry then.

I then tried
````
"require": {
	"themattharris/tmhOAuth": "*"
}
````
and still got the 0.7.2 branch.

I then reviewed https://github.com/themattharris/tmhOAuth/blob/master/composer.json and see that the package requires itself! (https://github.com/themattharris/tmhOAuth/blob/master/composer.json#L28). It also hardcodes the version, and the classmap is wrong.

I tested the updated `composer.json`, and it works fine. Please use it.