mmsd: a few fixes

These are a few fixes for mmsd:

• A memory leak I saw
• It turns our I did not fix the MIME type issue, this is a proper fix.
• Use g_str_has_prefix instead of g_str_match_string, since it is faster and works fine.

added 3 commits

• d8319c22 - mmsd: use g_str_has_prefix instead of g_str_match_string
• 0fc53302 - mmsd: clean up mime_type detection
• 64fda49e - mmsd: fix memory Leak

Compare with previous version

merged

thanks. merged