added methods for updating and deleting instance metadata
added methods for updating and deleting instance metadata

wathsalav/xos,jermowery/xos,zdw/xos,open-cloud/xos,xmaruto/mcord,cboling/xos,open-cloud/xos,zdw/xos,wathsalav/xos,zdw/xos,cboling/xos,xmaruto/mcord,wathsalav/xos,opencord/xos,xmaruto/mcord,opencord/xos,wathsalav/xos,cboling/xos,open-cloud/xos,cboling/xos,jermowery/xos,jermowery/xos,zdw/xos,opencord/xos,cboling/xos,jermowery/xos,xmaruto/mcord