enhance rhsecapi cmdline arg parsing of CVEs by running list through rhsda.extract_cves_from_input()

[ryran]

Currently:

$ rhsecapi -f bugzilla cve-2999-bad cve-2016-9401,CVE-2016-9374.json /CVE-2016-9074,CVE-2016-9064
[NOTICE ] rhsda: Valid Red Hat CVE results retrieved: 0 of 3
[NOTICE ] rhsda: Invalid CVE queries: 3 of 3

CVE-2999-BAD
  Not present in Red Hat CVE database
  Try https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2999-BAD

CVE-2016-9401,CVE-2016-9374.JSON
  Not present in Red Hat CVE database
  Try https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-9401,CVE-2016-9374.JSON

/CVE-2016-9074,CVE-2016-9064
  Not present in Red Hat CVE database

After the change:

$ rhsecapi -f bugzilla cve-2999-bad cve-2016-9401,CVE-2016-9374.json /CVE-2016-9074,CVE-2016-9064
[NOTICE ] rhsda: Found 4 CVEs on cmdline
[NOTICE ] rhsda: Valid Red Hat CVE results retrieved: 4 of 4

CVE-2016-9401
  BUGZILLA: 1396383

CVE-2016-9374
  BUGZILLA: 1396410

CVE-2016-9074
  BUGZILLA: 1396548

CVE-2016-9064
  BUGZILLA: 1395060