fixes RM7926 msfconsole search busted

fixes http://dev.metasploit.com/redmine/issues/7926 which prevented a
proper search using:
msf> search exploit:type app:server

## Verification
````
### before
  - [ ] msf> search type:exploit app:server returns nothing, but app:client returns lots
### after
  - [ ] msf> search type:exploit app:server returns lots; app:client returns lots
further confirmation:  
  - [ ] msf > grep ms11_050 search type:exploit app:client
=> returns 1 module, which is indeed a "client-side"
  - [ ] msf> grep netapi search type:exploit app:server
=> returns 3 "server-side" exploits
````