Remove unnecessary require from active_support/inflector/methods.rb

`active_support/inflections` already requires
`active_support/inflector/inflections`. There's no need to require it in
`active_support/inflector/methods`.
change to destructive `deep_symbolize_keys` after https://github.com/rails/rails/commit/df24b8790f22384a068fece7042f04ffd2fcb33e which allows to do so. This helps to avoid extra hash object creation, by symbolizing inplace
make "rails dbconsole" work with activerecord-postgis-adapter
Add test for AR::CounterCache.update_counters
Refactor AR's counter_cache_test.rb test
Use Range#cover? for Numeric ranges (tests via endpoints) and use Range#include? for non-numeric ranges

added changelog message
Remove OracleDatabaseTasks was deprecated, because this was provided by 3rd-party.
Remove SqlseverDatabaseTasks was deprecated, because this was provided by 3rd-party.
Remove FirebirdDatabaseTasks was deprecated, because this was provided by 3rd-party.
fix serialization type cast when value is already unserialized
add test for 9041454def79d8e61cabe49e7c5cb72cef29138b
Added a warning about #1769 to the routing guide.
Use symbols instead of strings

ActiveSupport::Concern is used all over Rails
This PR will only create 3 new objects as keys are never recreated and
are not subject to garbage collection.

The strings were being uniquely created and garbage collected. I don't
have any performance numbers but this should be better than all of the
GC.
Calls to the application constant have been refactored to use
Rails.application when drawing routes and creating other configurations
on the application.
Merge pull request #142 from codyrobbins/master

Added a warning about #1769 to the routing guide
more guidelines for command line
correct documentation about active_record behavior
`existant` => `existent`
replace version 3.2.3 by 4.0.0.beta in command line
`dasboard` => `dashboard`