Improve for correct working with all RADIUS AV pairs

In this pull request I`d correct work with retrieved from RADIUS AV pairs for modules auth_radius, misc_radius and peering. Now this modules correctly put to $avp() all retrieved params:
- integer name and integer value
- integer name and string value
- string name and integer value
- string name and string value
All above said and for SIP-AVP params too.