Allow a route to have :format => true

Normally I would have done this in master, but there was already
a guide with wrapped content, so worked here. I am going to
cross-merge now.

When format is true, it is mandatory (as opposed to :format => false).
This is currently not possible with resource routes, which automatically
make format optional by default.

This reverts commit 6f29b356.

Reason: Changelogs are not meant to be changed in docrails.

Merge pull request #2245 from davidtrogers/constraints_block_passed_to_following_routes_in_same_scope

Memoizing @blocks & disposing of constraints options properly

addresses issue #1907 - any routes that follow a route with a constraints
  block are inheriting the previous route's constraints.

Use shorter class-level File methods instead of going through File.stat

Fix after_initialize and Base.create edge case

provide more explicit test names

Add test checking that precompiling assets performs caching

This reverts commit 1e5fa59d.

Reason: It's somewhat a grey area. We don't really want to tell the
users how they want to use the terminal.

This reverts commit e3dbe66e.

Reason: Code changes are not allowed in docrails.

Bring back the ability to provide :order for update_all

Make polymorphic_url calls go through application helpers again.

This brings back the ability to overwrite/extend url generating methods in application heleprs.

- includes 3 tests

Rewrote entire section including example code, error message, and work
around.

Ordering with extra spaces was raising a SQL exception