encodeHex function
new constructor taking appsecret
wow, much eclipse, very broken
updates
working fixing tests
clean up
decremented version number
added static method for use outside of DefaultFacebookClient
Add contentType to BinaryAttachment which will be used to send along with POST requests if it's not null.

The issue was that if there is no content type specified in POST body, then Facebook cannot recogonize it. Esp when you send a picture in private message, the picture will be showed as a file in attachment instead of rendering in the conversation directly.
Javadoc updates
Additional error checking and formatting cleanup for pull request
Javadoc fixes
Merge branch 'master' of https://github.com/UglyTroLL/restfb

# By Zhibo Wei
# Via Zhibo Wei
* 'master' of https://github.com/UglyTroLL/restfb:
  Add contentType to BinaryAttachment which will be used to send along with POST requests if it's not null.
Formatting tweaks for pull request
Updated changelog to reflect latest contributions
Code formatting cleanup
Renamed makeAppSecretProof to obtainAppSecretProof and declared it at the FacebookClient level.  Also have it driven by parameters so callers can use it more clearly, e.g. new DefaultFacebookClient().obtainAppSecretProof(MY_ACCESS_TOKEN, MY_APP_SECRET);
Modify appsecret-proof tests to reflect signature changes
Fix for #89 (Add subCode to FacebookOauthException).  Moved getErrorCode() and getErrorSubcode() up into FacebookGraphException since it might be possible for non-FacebookOAuthExceptions to have these fields
Doc updates for 1.6.13