(maint) Extend require_library_or_fail to case where gem name != library name

Note that some gems are named something other than their actual library
name. E.g. there is a ruby gem called 'jira' that you would load with
'require jira', but that is not the gem we want. Instead we want the
gem called 'ruby-jira' which is also loaded with 'require 'jira'.
Because ruby. Yay!

Prior to this patch, the 'require_library_or_fail' utility method
assumed the gem name and the ruby name were the same. This supports
the case where they are different (hopefully leading to a more useful
error message). This patch also flips tickets.rake over to use
'require_library_or_fail'.
(maint) Add Pkg::Util.get_var to get an env var (and fail if missing)
(maint) Add ability to have a project-specific release step

PuppetDB has a project-specific build step (updating DuJour). We should
try to keep project-specific build steps pretty limited, so I'm hoping
this isn't too much of a slippery slope. If there's a lot of need, we
may want to restructure this code accordingly.
(maint) Require a real jira user to create tix (rather than gepetto_bot)
(maint) Add reminder about the msi package
(maint) Fix Nick F's jira username