Revert "Feature: make user check case-insensitive"

This reverts commit aac14d4d84b52bec3f57a402852daeccc5c8c21f.
Revert "Feature flags: add subreddit filtering"

This reverts commit f41d0ad229f3a38b1a567685519540ac340f5489.
install-reddit: Add REDDIT_PLUGINS variable.

This variable is used to tell the build system what plugins to clone and
register with the make process. It also works when the plugins are
already cloned and have local modifications.
install-reddit: Make idempotent

These changes make it so the install-reddit script is mostly self
healing and can be run many times in a row on the same machine. This
allows for more rapid iteration on development of the build process and
also easier updates for end users.
install-reddit: Domain configuration for .update

Added automatically updating the domain field in development.update
based on what is specified via environment variable to avoid
inconsistencies.
Fix OSX+Vagrant Captcha module loading problem