(#21970) Comment fixup

The REST certificate endpoint supports only find, not save.
(#21970) Move supported formats into the per-endpoint md
(#21970) Add markdown doc for certificate endpoint

Add markdown doc and add link from index markdown page.
(#21970) Correct markdown and add explanatory text
(#21970) note that the certificate is in pem format
(#21970) add 'Supported HTTP Methods' section
Merge pull request #1823 from kylog/issue/21970-document-certificate

(#21970) document certificate endpoint
(#21970) document response when master != ca
Merge pull request #1824 from kylog/issue/21970-document-certificate

(#21970) document response when master != ca
(#22079) Fix HashArrayAccess produces :undef when value is false

It should naturally have produced false. The test for "having value" was
wrong and equated nil with false.
Merge pull request #1825 from jpartlow/issue/master/22079-fix-hash-array-access

(#22079) Fix HashArrayAccess produces :undef when value is false
(maint) extract test into setup and test cases
(maint) extract reusable helper methods
(maint) expand fixture paths in specs for windows
Merge pull request #1826 from adrienthebo/maint-windows_path_spec_failures

Refactor network/http/connection peer verify specs
Kerberos: agents without certs, with SPNEGO

This *prototype* change demonstrates a minimal set of edits to support
SPNEGO/GSSAPI/Kerberos authentication of agents to masters instead of agent
certificates. It is not meant to be a shippable patch. There are two primary
changes:

1) Add SPNEGO/gssapi support to Puppet::Network::HTTP::Connection.

2) Add an agent option to run without a certificate. For now stub out the
   certificate creation and checking logic.

In addition to all the TODOs in the code this change is also missing tests.
Kerberos: support REMOTE_USER, SAM account to hostname lookup

This *prototype* change demonstrates a minimal set of changes to puppet master
necessary to support apache mod_auth_kerb based agent authentication. This patch
is not intended for submission. The modifications consist of two changes:

1) During request authentication use the REMOTE_USER environment variable set by
   mod_auth_kerb as a lower priority alternative to SSL certificates.

2) Add a user to hostname lookup facility. This takes the REMOTE_USER value and
   looks up the hostname via LDAP. This implementation is a "toy" that requires
   a password in the master config.