Fix index creation with uniqueness constraint
Fix index creation with uniqueness constraint

ReactiveMongo/ReactiveMongo,mcveat/ReactiveMongo,charleskubicek/ReactiveMongo,ReactiveMongo/ReactiveMongo,reactific/ReactiveMongo,maowug/ReactiveMongo,ornicar/ReactiveMongo,cchantep/ReactiveMongo,sh1ng/ReactiveMongo,cchantep/ReactiveMongo,viktortnk/ReactiveMongo,lunatech-labs/lunatech-reactivemongo,ornicar/ReactiveMongo,bfil/ReactiveMongo,maxime-gautre/ReactiveMongo,charleskubicek/ReactiveMongo,mcveat/ReactiveMongo,avdv/ReactiveMongo,maxime-gautre/ReactiveMongo,viktortnk/ReactiveMongo,avdv/ReactiveMongo,maowug/ReactiveMongo