mysqldb: Fix message_get_property() to not crash in case proptag requested is not found

Also add small optimisation while comparing properties.name
with precalculating requested proptag name length

Signed-off-by: Kamen Mazdrashki <kmazdrashki@zentyal.com>
ldb_db: get_mapistoreURI() fix potential memory leak

afaik, get_mapistoreURI() with mailboxstore = false is not used
anywhere but still

Signed-off-by: Kamen Mazdrashki <kmazdrashki@zentyal.com>
Merge pull request #27 from kamenim/kamenim/openchange-fix-segfault

fix segfault when getting message properties