fix critical bug which allowed use any character in hostnames. Also, fixes #20
fix critical bug which allowed use any character in hostnames. Also, fixes #20

Conflicts:
	ddserver/resources/templates/addhost.html

ddserver/ddserver,reissmann/ddserver,reissmann/ddserver,iSC-Labs/ddserver,ddserver/ddserver,ddserver/ddserver,iSC-Labs/ddserver,iSC-Labs/ddserver,iSC-Labs/ddserver,ddserver/ddserver,reissmann/ddserver,reissmann/ddserver