Fix inability to reply

replyTo input field is read by JS to submit which post we're replying to

Bug: 65060
Change-Id: I7fed8c142f9618c5fd4e77b85a17162c18c56c99
(cherry picked from commit 59ec58e041f088597eef959930546be4200a02cc)
Fix not being able to submit new topics

flow_definition contains a serialized UUID for discussion's definition_options.
If you've set up Flow a long time ago, that UUID will have been 128-bit.
Depending on when exactly you ran this, propery $hexValue may also be stored
(with an old 128-bit UUID hex representation)

When we merged to 88-bit UUIDs, we've added some B/C code to convert 128-bit
binary values to 88-bit binaries. The hex property was left untouched.

We've recently optimized UUID to not always convert from/to binary anymore,
unless when only needed. This caused $hexValue to be used to convert to
alphanumeric, instead of binary.
Binary was the only format with B/C code for 128-bit to 88-bit, not hex.
This resulted in a 128-bit alphanumeric value being returned.

When, in turn, using that value to find topic definitions (definition_id) in
order to submit a new topic, we failed :)

Bug: 65062
Change-Id: I65e8e51c5d854e40556c7376291762c98836c200
(cherry picked from commit 0ab15d68db52ffb6552ad9dba7d19c3985de5072)
Merge "Fix inability to reply" into wmf/1.24wmf4