#480 - Making the ERBRenderer issue not happen on dev.

The issue is described here: https://github.com/gocd/gocd/issues/480. Making
it not happen on the development server.
Merge pull request #589 from pshivana/rails4_defect_fixes

#529 Fixed
Merge pull request #562 from arvindsv/hide_erb_renderer_issue_on_dev_server

#480 - Making the ERBRenderer issue not happen on dev.
Merge pull request #590 from pshivana/rails4_defect_fixes

#529 fixing specs
Merge pull request #591 from pshivana/rails4_defect_fixes

Rails4 defect fixes
corrected spelling
Rendering history action without layout

By default, this action was using application layout which caused the Stage History ajax call to show layout until the autoRefresh kicked in. Ref: Issue 594
Fixing Hound feedback
Merge pull request #596 from sachinsudheendra/bug-594

#594 - Rendering history action without layout
#000 - Fix Rails logging.

1. Development server no longer logs into /tmp/debug.log. Removed stale
   log4j.xml files from gadgets engines. It will now be in server/go-server.log
   and DEBUG logs are turned on by default.

2. For production, RAILS_LOG_LEVEL environment variable is introduced. It sets the
   log level. However, that decides what Rails sends to Log4J.  Log4J has its own
   level (in log4j.properties) which decides what it appends to the file appender.
   Usually these two need to be in sync. You can set one to a high level and the
   other to a lower logging level and the lower one will will (meaning, WARN will
   be chosen instead of INFO instead of DEBUG, etc).
#000 - Fix inline ERB partials.

Fix the inline of partials done in the package step of Go (where
render :partial => abc gets inlined into the place it is called.

Previously patterns of this format were supported:
<%= render :partial => ... %>
<%= render_json :partial => ... %>

Fixes are:

1. Handle 'render(:partial => ...)'.

2. Handle 'render_json(:partial => ...)'.

3. Handle '<%== render_json(:partial => ...)' since it is used by ERB of Rails 4.
#000 - Handle empty string for RAILS_LOG_LEVEL.
#000 - Fix null check in HostNameValidator.

Was showing up as a 500 Internal Server error when you clicked 'Send Test Email'
in Server Configuration page, without entering any hostname.
Merge pull request #605 from arvindsv/fix_empty_hostname_validation

#000 - Fix null check in HostNameValidator.
Merge pull request #600 from arvindsv/fix_rails_logging

#000 - Fix Rails logging.
Merge pull request #604 from arvindsv/fix_inline_partials

#000 - Fix inline ERB partials.