Use more widely supported options for the "tr" command line utility b…y removing the use of the character class representation option. [:space:] => "\t\r\n\v\f"
Updated to use suggested export _H1 env var to supply Authorization Basic credentials. This undocumented support for Basic Authorization, ContentType, etc. needs to be documented in DNSAPI Dev Guide. Removed two stray debugging lines.
Created _get_root() that tests the requested host is a subdomain to the domains hosted on MailinaBox (MIAB) DNS Server. Created common _miab_rest() used with dns_miab_add(), dns_miab_rm() and _get_root(). Also created barbaric _is_json() to test the response given by the MIAB Custom DNS API at least looks like a JSON file. We should add a hint to use _normalizeJson with JSON responses so _startswith, _endswith won't perplexingly fail.