Fix to disallow server name with all blank spaces (v3 API)

Prevents a server name to be created, updated or rebuilt with all blank characters.
A fix for the V2 API was merged in commit 98ff29d13af9e0c1fa96e49e68939634c24ad2c3
but was not applied to the V3 API.

Fixes bug 1212096

Change-Id: Ibaf0ca7a766b6a279a83f56165edbf8ced29d5fa
Merge "Fix to disallow server name with all blank spaces (v3 API)"