Work with Orchard 1.7

Modified to work with 1.7. Other changes include:
+ Exclude the _Backup folder, which was created by Orchard to store old
modules
+ Import from code: beside the 'Generate from source' that scans the
whole site, new options were added to generate from a specific module or
theme
+ maybe more, don't remember :P
Create README.md
Merge pull request #34 from pilgylis/master

Added support for Orchard 1.7
(didn't check it myself)