Add define.amd property.

This is part of the API
https://github.com/amdjs/amdjs-api/wiki/AMD#defineamd-property-


Also, We won't have to create custom shims for libraries which already have
support for amd in their bower dist.
Merge pull request #4 from abuiles/define-amd

Add define.amd property.
Don't special case top-level modules
Merge pull request #6 from mmun/top-level

Don't special case top-level modules
add `testem` to run tests more easily.
Merge pull request #8 from yamadapc/master

add `testem` to run tests more easily.
Revert "Merge pull request #4 from abuiles/define-amd"

This reverts commit ec3cc31626df4c7024730845a212efd1c1ee1c4c, reversing
changes made to 666bdca45da750cb7aceb7824ff7c71523c4a5a2.
Merge pull request #9 from abuiles/revert-define-amd

Revert "Merge pull request #4 from abuiles/define-amd"