Merge pull request #79 from cablelabs/dlnasrc-69-common-refactor

Address dlnasrc Issue #69 - simplified logic by creating overall start, ...
Treat GST_FORMAT_DEFAULT as unsupported.  Modified dlna_src_assign_content_info() to be an else if rather than just if statements.
Changed 3 to 2 since there are two formats supported.
using theirs
Fixed mismatch on number of formats, from 3 to 2