Fix test as one more has_many added

Synchronize the gemspecs since CHANGELOG has been renamed to CHANGELOG.md

Reasons:

 * Markdown reads well as plain text, but can also be formatted.
 * It will make it easier for people to read on the web as Github
   formats the Markdown nicely.
 * It will encourage a level of consistency when people are writing
   CHANGELOG entries.

The script used to perform the conversion is at
https://gist.github.com/1339263

This is to avoid confusing newbies, and to be consistent with the fact
that other options like :foreign_key already allow a symbol or a string.

Remove 'size' attribute from number_field form helper fixes #3454

Sexier migrations

f.number_field generates <input type="number", size="30"../> which is
invalid HTML5. See: http://dev.w3.org/html5/spec/Overview.html#number-state

Preserve SELECT columns on the COUNT for finder_sql when possible

Stub find_template so that when handle_render_error is called in ActionView::Template, we get to see the actual underlying error rather than a NoMethodError.

This shows an encoding bug on Ruby 1.9.3.

Building the conditions of a nested through association could
potentially modify the conditions of the through and/or source
association.

This is a Bad Thing.

If a record is removed from a has_many :through, all of the join records
relating to that record should also be removed from the through
association's target.

(Previously the records were removed in the database, but only one was
removed from the in-memory target array.)

Fixes #3425.

Fixes creating records in a through association with a polymorphic source
type.

treat USAGE as an ERB template

This reverts commit 8a6acc17.

Ensure that the format isn't applied twice to the cache key, else it becomes impossible to target with expire_action.

dump_schema_information: explicitly order inserts into schema_migrations 

This change reduces churn in the db/development_structure.sql file when using :sql as
active_record.schema_format, and makes comparing diffs much easier.

Test ensures the output SQL-statements are lexically ordered by version.

Refactor ActiveSupport::Cache::FileStore.

fix a document for :compress_threshold. DEFAULT_COMPRESS_LIMIT is 16K.

avoided to call `Marshal.dump` twice

This commit also implements a faster version of #demodulize I was unable
to isolate with git add --patch.

Not a big fan of the name #deconstantize. It complements #demodulize
getting rid of the rightmost constant, hence the name, but it is
unrelated to the well-known #constantize. So unsure. Could not come
with anything better, please feel free to rename.

fix a document for race_condition_ttl. ActiveSupport::Cache::MemoryCache isn't exist.

removed a reference to SynchronizedMemoryStore and CompressedMemCacheStore