Remove j alias for ERB::Util.json_escape
Fix GH #4259. We must remove table_name_prefix and table_name_suffix, when we execute schema dumper.
Fix eagerly loading associations without primary keys
Prevent concurrent compilation of templates - closes #6400

This addresses an issue where in multi-threaded environments
multiple threads can attempt to compile a template at the same time,
which occasionally causes particular templates to end up in a bad
state.

So, add synchronization such that only a single thread can attempt to
compile a template at one time.
Make the Resolver template cache threadsafe  - closes #6404

The Template cache in the Resolver can be accessed by multiple threads
similtaneously in multi-threaded environments. The cache is implemented
using a Hash, which isn't threadsafe in all VMs (notably JRuby).

This commit extracts the cache to a new Cache class and adds mutexes to
prevent concurrent access.
More granular locking of the Resolver template cache

In order to avoid holding a global lock when doing template
resolution, instead add individual locks on a per cache entry
basis. The global lock is now only used for manipulation of the main
cache data structure.
Improve the readability of the Resolver change detection code
Cache metadata in advance to avoid extra sql statements while testing.

Reason: If metadata is not cached extra sql statements
will be executed, which causes failures tests with assert_queries().
Make connection pool fair with respect to waiting threads.

The core of this fix is a threadsafe, fair Queue class.  It is
very similar to Queue in stdlib except that it supports waiting
with a timeout.

The issue this solves is that if several threads are contending for
database connections, an unfair queue makes is possible that a thread
will timeout even while other threads successfully acquire and release
connections.  A fair queue means the thread that has been waiting the
longest will get the next available connection.

This includes a few test fixes to avoid test ordering issues that
cropped up during development of this patch.
AR::Relation#model would be a better API than AR::Relation#klass
add convenience methods for checking migrations

if a rails project needs to be migrated ActiveRecord::Migrator.needs_migration? will be true or false if the current version matches the last version. 
remove unnecessary text
bundle exec is needed even if running a single test.
Merge pull request #103 from Vanuan/contributing

bundle exec is needed even if running a single test.
Add a note about JavaScript runtime
remove double hyphen that doesn't allow properly parsing
add example to AS::Gzip
add instance_accessor option to ActiveSupport::Configurable#config_accessor

Changes:

* Add `instance_accessor` option to opt out of the instance writer and
  instance reader methods.
* Raises a NameError if the name of the attribute is not valid.
* Update documentation and tests.
* Add CHANGELOG entry in activesupport.
bundle exec rake assets:precompile shouldn't fail quietly.

If JavaScript runtime is not installed, execjs fails with error quietly,
while tests continue to run. This should not happen since it causes tests
to fail for unknown reason (#6621).

This commit assures that if JavaScript runtime is not installed, an assertion
is raised.
Merge pull request #6638 from frodsan/config_accessor

add instance_accessor option to config_accessor