Add /identities endpoint for approved ID codes

[kaarmann]

It would be useful for the app to have a list of identities, who are approved on the system. In the future this would allow searching for people and businesses by name or by id code.

e.g.

/identities returns all approved id codes
/identities/38008030265 returns name, status, avatar for me
/identities/search/?id="38008" returns all Aug 1980 born males
/identities/search/?name="Toomas"&id="38008" returns all Aug 1980 born males who'se name contains Toomas