add a "step" argument to range()

This patch adds an optional "step" argument to the stdlib range()
function.  There is no change to the default behavior of the function;
however, passing a numeric "step" argument invokes the Ruby Range#step
method, e.g.

    range("0", "9", "2")

returns

    [0,2,4,6,8]
(#19272) Add has_element() function

It is exceptionally difficult to determine if an array contains an element matching a specific value without an iteration or loop construct.

This function is the Puppet equivalent of Array.includes?(foo) in Ruby.  The implementation is a verbatim copy of has_key() with the minor modifications needed to support arrays instead of hashes.
Merge pull request #130 from jhoblitt/has_element

(#19272) Add has_element() function
Revert "Merge pull request #130 from jhoblitt/has_element"

This reverts commit f7a18189ec338b01b0fc89d75def832753af3868, reversing
changes made to 36a7b29630a4d4de17af79b5dd4e9491ec20b123.

I'm reverting this change because of concerns raised by Peter Meier that
it duplicates the "in" operator in the DSL.  The "in" operator is new
information that I did not posses when I made the decision to merge.
Because of this new information I'm un-merging and continuing the
discussion in the comments of
https://projects.puppetlabs.com/issues/19272

Reference: GH-130
changed .count to .size to support legacy ruby
changed .count to .size to support legacy ruby
Merge branch 'mhellmic-2.x' into 2.x

* mhellmic-2.x:
  changed .count to .size to support legacy ruby
Merge branch '2.x' into 3.x

* 2.x:
  changed .count to .size to support legacy ruby
Merge branch '3.x' into 4.x

* 3.x:
  changed .count to .size to support legacy ruby
Merge branch '4.x'

* 4.x:
  changed .count to .size to support legacy ruby

closes #131
(maint) Add Ruby 2.0.0 to Travis build matrix

Without this patch we're not testing against Ruby 2.0.0 which has recently been
released.  This is a problem because we'd like a way to be notified if a change
set breaks compatibility with future supported versions of Ruby.

This patch should not be taken as an indication that we fully support Ruby 2.0,
just as an indication that we plan to in the future.

This patch also tightens up the specifications of the build matrix.  In
addition to testing against the specific Puppet dependency versions, we're also
testing against the latest 2.7.x release and the latest release.
Merge branch 'maint/3.x/ruby_two_travis' into 3.x

* maint/3.x/ruby_two_travis:
  (maint) Add Ruby 2.0.0 to Travis build matrix
Merge branch '3.x' into 4.x

* 3.x:
  (maint) Add Ruby 2.0.0 to Travis build matrix
Merge branch '4.x'

* 4.x:
  (maint) Add Ruby 2.0.0 to Travis build matrix

Conflicts:
	.gitignore
	.travis.yml
	Gemfile
Add missing documentation for validate_augeas and validate_cmd to README.markdown
Merge pull request #132 from raphink/dev/missing_doc

Add missing documentation for validate_augeas and validate_cmd to README.markdown
Add contributing document

Copied from the same one included in Puppet and Facter.

[ci skip]
Fix number of arguments check in flatten()

The function only uses the first argument, so raise an error with
too few arguments *and* with too many arguments.
Merge branch 'pull-98' into 2.x
Merge branch '2.x' into 3.x