Correct bundle-config manpage

It is not possible to set BUNDLE_GEMFILE using bundle-config, so don't
tell users that it is. [#1315]
Merge pull request #2917 from urbanautomaton/fix-bundle-config-documentation

Correct bundle-config manpage
Redirect to bundler.rubygems.org if the host is rubygems.org
Merge pull request #2918 from bundler/redirect_to_bundler

Redirect to bundler.rubygems.org if the host is rubygems.org
Version 1.6.0.rc2 with changelog
Add missing switches documentation for bundle-install(1)
Add missing switches documentation for bundle-update(1)
Report docs change in CHANGELOG
Remove `--frozen` switch documentation

...since it's not user facing.
Merge pull request #2925 from as-cii/update-man-pages

Update man pages with missing switches
Avoid threequals operator where possible
Report threequals removal on changelog
Merge pull request #2929 from as-cii/avoid-threequals

Avoid threequals operator where possible
Fix redundant and slightly silly descriptions in gem spec template
Merge pull request #2932 from stevecj/tweak-gem-template-spec-descriptions

Fix redundant and slightly silly descriptions in gem spec template
Link to Freenode's web chat
Merge pull request #2935 from mathonsunday/master

Link to Freenode's web chat
Version 1.6.0 with changelog
Remove deprecation warning caused by use of failure_message_for_should

- RSpec has replaced failure_message_for_should with failure_message in
  https://github.com/rspec/rspec-expectations/commit/bfe92020d5569350c1382235feb9b113907fa2db
- This change removes deprecation warning caused by https://github.com/rspec/rspec-expectations/commit/cd0d347d3115f8aad801e6dc8fe2a311d75626bd#diff-a51020971ade2c87f1d5b93f20d711c7R207
Merge pull request #2953 from prathamesh-sonpatki/remove-deprecatio-warning

Remove deprecation warning caused by use of failure_message_for_should