Sqlite::truncate(): Verify `sqlite_sequence` exists before _execute()

`sqlite_sequence` is a dynamic table that's only available when a table in
the database use an auto increment field.  For some cases, eg: databases that
exclusively use uuid for primary keys, this table won't exist and
truncate() call will fail with:

  Error: SQLSTATE[HY000]: General error: 1 no such table: sqlite_sequence
Reduce variable use/duplicate code.
Added/removed newlines to make the code more readable.
flushMethodCache not working if called before cacheMethod

When calling flushMethodCache it correctly empties self::$methodCache but if cacheMethod is called afterwards self::$methodCache gets populated with data from the Cache.
Improved wording of Model::invalidFields()

Inspired by
http://book.cakephp.org/2.0/en/models/data-validation/validating-data-from-the-controller.html#validating-data-from-the-controller
Merge pull request #1645 from ShinKenDo/patch-1

Improved wording of Model::invalidFields()
Fix wording and remove trailing spaces.
removed duplicate test case

Was exact duplicate of case starting line 692
Merge pull request #1646 from spiliot/patch-1

removed duplicate test case in CakeRequest Referer
Fix label element for attributes not matching their inputs.

Radio elements would contain ModelModelFieldValue instead of
ModelFieldValue like they should. This was caused by the fix for #3936
and lack of tests for create() + radio().

Fixes #4071
cs corrections, bool to boolean and int to integer.
more cs
address casting cs
Merge pull request #1648 from dereuromark/master

cs corrections
Corrected some grammar in the JsonView class doc blocks
Updated doc block for JsonView's subDir property
Merge pull request #1650 from bcrowe/fix-jsonviewdocs

Corrected some grammar in the JsonView class doc blocks
Update docs for HttpSocket methods.

delete() uses the request body, not the query string.
Updated CakeTime::i18nFormat() doc block description
Merge pull request #1652 from bcrowe/fix-caketimedocs

Updated CakeTime::i18nFormat() doc block description