Merge branch 'hotfix/issues-image' into develop

Updated issues image
Merge branch 'hotfix/issues-banner' into develop

Revert issues banner
Created Makefile target for homepage

- Grabs most recent blog and security announcements, and updates the
  homepage with them.
Updated Changelog module

- Fetch only one version at a time, and incrementally add to changelog
  data files
- Switch ZF1 changelog strategy based on version (< 1.12.4 uses JIRA;
  otherwise GitHub)
- Abstract logic into separate methods when possible
Simplify console usage

- to: `changelog fetch --version=`
- Controller now determines what method to call, and passes version to
  method
Added `changelog` target to Makefile
Refactored manual/apidoc version configuration

- API doc version mapping is now configuration driven.
- Moved static information into separate configuration files, which are
  then included by the module-specific configuration file overrides.
Created `download-version` target

- Alls on new script, `bin/generate-download-versions.php`, which uses
  the version and date passed in order to add to the list of available
  versions.
Renamed script to `update-download-versions.php` for consistency
Added `manual-version` target

- Invokes `bin/update-manual-versions.php` in order to generate an
  appropriate configuration file
- Makefile target directs output to a temp file, and then copies it over
  the original on success only (altered `download-version` target to do
  this as well)
- Altered `checkVersion` target to create `VERSION_MAJOR` and
  `VERSION_MINOR` variables
Renamed `checkVersion` to `check-version` for consistency
Created `apidoc-version` target

- Invokes new script, `bin/update-apidoc-versions.php`, which updates
  the version mapping for API docs
- Updated `.PHONY` and `all` targets to incorporate all targets created
Updated Makefile documentation

- Documented available arguments and targets
Updated README with new instructions
Merge branch 'feature/release-makefile' into develop

Created Makefile for updating release version, changelog, manual/apidoc version
mappings, and the homepage.
Merge branch 'develop'

Merged in Makefile feature for easing deployment of releases.
Added link to modules.zf.com in footer
Add paragraph about ZF2 modules site in participate section
Merge branch 'hotfix/modules-site-references'

Add references to modules.zf.com
Created 2.1.5 release blog post