Added ImgurAccount object

We can now get Imgur user account information with the ImgurAccount
object.

Test in ImgurDotNetTest with the 'gac' command.
Added ImgurComment object

We can now get Imgur comment information with the ImgurComment object.

Test this in ImgurDotNetTest with the 'gc' command.
Update README.md

Updated readme to reflect feature additions.
Update README.md

Fixed typos
Merge pull request #2 from moyerr/Add-More-Data-Models

Add more data models