NSString+DN.m:dnComponents method failed to parse DNs which contain commas

NSString+DN.m:dnComponents failed to parse for example following DN:

dn: CN=Tkac\, Adam,OU=ITZ,DC=geodis,DC=cz

The DN was splitted into

"CN=Tkac\", "Adam", "OU=ITZ", "DC=geodis", "DC=cz"

which is apparently wrong. Now the DN is splitted correctly into

"CN=Tkac\, Adam", "OU=ITZ", "DC=geodis", "DC=cz"

Signed-off-by: Adam Tkac <vonsch@gmail.com>
Signed-off-by: Ludovic Marcotte <lmarcotte@inverse.ca>
Fixed memleak in patch from #2152 + formatting changes.