Some typos and some proposals chapter 06 - 14.

Signed-off-by: Martin Weissenboeck <mweissen@gmail.com>
ch7 validators organised by category for easier discovery.
Correction to IS_IN_SET when combined with numerical validators, thanks Horst.
Ch 6 Noted that del record with shortcut [id] doesn't work with versioning.
Corrected a mistake.
Book said that for authorization of downloads one has to set the "authorization" attribute for the corresponding field. However, looking into the source code (dal.py, line 9852), the attribute that is actually checked is called "authorize" instead.
SQLFORM formstyle can also be bootstrap
Merge pull request #164 from mweissen/Sometypos

Some typos and some proposals for chapter 06 - 14.
Merge pull request #167 from timrichardson/fixes_20140216

ch7 validators organised by category for easier discovery.
Merge pull request #168 from ghofferek/master

Corrected a mistake (Mistmatch between source code and book)
Merge pull request #170 from timrichardson/sqlform_bootstrap_style

SQLFORM formstyle can also be bootstrap
Merge remote-tracking branch 'upstream/master'