Added checks for plugin dbus iface creation and result from msyncd

Signed-off-by: Sateesh Kavuri <sateesh.kavuri@gmail.com>
Added and updated documentation for buteo syncfw and also oop plugins

Updated the documentation to include:
* Way to create plugins
* Way to use the buteo tools to generate plugin code
* Added the syncfw architecture documentation
* Added the way to create an out of process plugins

Signed-off-by: Sateesh Kavuri <sateesh.kavuri@gmail.com>