[imp #107] Remove URL encoded data in blue-sync

All of blue-sync module now only deals with UTF-8 strings.
The compatibility layer for old mobwrite protocol ensures that data is
encoded/decoded when needed.
Thus, the blue-sync core is much cleaner and easier to maintain.

Neil Fraser's DMP code has been modified so that it also only makes use
of UTF-8 strings.
Merge pull request #117 from tdurieux/wip-fix-107

[imp #107] Remove URL encoded data in blue-sync