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.