Refactored some of app cast parse functions to smaller targeted funct…

[jessek1]

…ions.

Added ability to pass in appcast data to Start().

Reason for this change is that I want to use my existing api client infrastructure to get the version info from my server. I also have a requirement to be able to send specific groups of users different versions to update to. By enabling the ability to pass in the AppCast data at the Start method, I can utilize the rest of the library and still rely on my api client libs to do any communication with the server effectively allowing me to determine what specific clients should get what version info etc.

Enables

• Existing api and security implementation
• Dynamic versioning based on specific client or any other attributes passed back to server