(maint) docs for admin API + /environment-cache

* Add docs on the new /environment-cache endpoint.

* Update the config doc with more detail about configuring the admin
  API.

* Minor formatting / wording fixes in the /certificate_status section.
DOC-1281: edits for Puppet Server external_ca_config
DO-1281: Puppet Server docs, external_SSL_termination

Edit and reorg of external_SSL_termination document for Puppet Server.
minor wording / capitalization fixes
DOC-1281: edits to external_ca_configuration and external_SSL_termination pages

Edits and adding a note about X-Client-Cert.
(MAINT) Update TK and Kitchensink dependencies
(MAINT) Added jira-ruby to Gemfile
(MAINT) Added some dev tools docs
Merge pull request #301 from KevinCorcoran/maint/docs-for-env-cache-endpoint

(maint) docs for admin API + /environment-cache
Merge pull request #303 from jbondpdx/ca-doc

DOC-1281: edits for Puppet Server external_ca_config
(SERVER-221) Initialize run_mode earlier

During some recent refactorings, we accidentally changed the behavior
for how we initialize Puppet's run_mode.  We weren't initializing
it as early as we had done in the past, so it was causing a very
minor and hard-to-repro bug in certain edge-case situations (such
as when a user had a puppet setting defined in both the `[main]`
and `[master]` sections of their puppet.conf file.

This commit moves the initialization up to happen a little earlier,
so that we'll be in `master` run_mode from the get-go.
Merge pull request #312 from dankreek/MAINT/add-gems

(MAINT) Added jira-ruby to Gemfile
Merge pull request #314 from dankreek/MAINT/adding-docs-to-dev

(MAINT) Added some dev tools docs
Merge pull request #310 from fpringvaldsen/update-to-tk-1.0.1

(MAINT) Update TK and Kitchensink dependencies
(MAINT) Fix Gemfile entry specifying beaker version.
Merge pull request #308 from cprice404/bug/master/SERVER-221-run_mode-not-initialized-soon-enough

(SERVER-221) Initialize run_mode earlier
Merge pull request #316 from waynr/maint

(MAINT) Fix Gemfile entry specifying beaker version.