Proposed changes

Bonjour Jean,

I started using your wonderful Ghost.py, and have improvements to propose. The changes are done against your dev branch.

Summary of changes:
Fix unsupported_content callback to support multiple calls (chunking)
Fix HttpResource to only convert content to unicode if content type is text
Add possibility to pass log handler as argument
Added clickLabel() and clickObj()

Merci,

Eryk Warren