[AD.yaml] Need to add more error messages for the field Domain Name

[Timur Nurlygayanov]

*Steps to reproduce*
{code}
        - name: name
          type: string
          label: Domain Name
          description: >-
            Enter a desired name for a new domain. This name should fit to
            DNS Domain Name requirements: it should contain
            only A-Z, a-z, 0-9, (.) and (-) and should not end with a dash.
            DNS server will be automatically set up on each of the Domain
            Controller instances. Note: Only first 15 characters or characters
            before first period is used as NetBIOS name.
          attributeNames: [name, domain]
          minLength: 2
          maxLength: 255
          regexpValidator: '^[0-9A-Za-z](?!--)[0-9A-Za-z\-]{0,13}[0-9A-Za-z]\.[0-9A-Za-z][0-9A-Za-z\-]{0,61}[0-9A-Za-z]$'
          errorMessages:a
            invalid: >-
              Only letters, numbers and dashes in the middle are
              allowed. Period characters are allowed only when they are
              used to delimit the components of domain style
              names. Single-level domain is not appropriate.
          helpText: >-
            Just letters, numbers and dashes are allowed.
            A dot can be used to create subdomains
{code}
Now we have only general error message for all types of errors. So if I type domain name like "morethen15symbolsbefore.dot" then I'll see general message, that doesn't contain any info about my mistake.

[Anastasia Kuznetsova (akuznetsova)]

Was fixed by Timur Sufiev 25/Nov/13 9:04 PM
https://review.openstack.org/#/c/58337/