master: Fix allcanchangequota parsing

Due to a bug, master tested export options for equality with
'allcanchangequota' only when they started with 'c'.

Obviously, it didn't work quite well. Fix it.

Change-Id: I147be3c50c20b32eb7abea6a4f42ff63bc55efb8
master: MessageBuffer typedef in matoclserv

Add

  typedef std::vector<uint8_t> MessageBuffer;

to make the code easier to write and read.

Change-Id: I570b79178785c35fed7ce29838866cd394dea040
master: Add basic quota support

Maintain a quota database in master and support setting/getting quotas.

No support for usage accounting and writing to metadata.mfs yet.

Change-Id: Icf56650e0557d26953dc5df67605c512633eb030
tools: Add quota support

Add tools mfssetquota and mfsrepquota that allow to control quota.

Change-Id: I152a86a9ecff1cc8c430a2f6900265af5e9e4a6f