Release 0.9 and proposed changes for 0.10

I have some more changes I'd like to contribute to omniauth.  Firstly I bumped the version to 0.9 in one of the commits so we can first release this version before I began mucking around in it.  Personally, I am using Lift 2.5.1.  Let me know what I need to do to help release the cross Lift versions, as I know that isn't automatic.

As for 0.10, the thrust of the change is to read from `SystemProperties` per [this thread](https://groups.google.com/d/msg/liftweb/5T_4xm1amr8/7T6ArZMic_kJ).  In my changes, Omniauth will try `SystemProperties` first before trying the Lift properties.  In my experience, I typically use system properties to configure deployment-specific settings, hence they are less broad than the Lift properties and seem appropriate to be given the highest precedence.  Personally, I only needed this behavior for `omniauth.baseurl`, but I thought it wise to have this behavior for all properties for consistency.  I'm open to change the precedence and so forth as the community sees fit.  At a the minimum, I need a way to specify `omniauth.baseurl` via system property, regardless of precedence.

In addition to those changes, I made some tweaks to the logging messages.

BTW, I also added my blog post on Dropbox in Lift at the bottom of the readme which some may find helpful.