Merge pull request #1141 from ADmad/3.0

Add info about options removal for FormHelper::create()
Switches all appropriate `echo`s to the short echo
fixes missing `=`
More missing `=` fixes
Merge branch 'feature-convert-to-short-echo' into 3.0

Merge pull request #1137 into 3.0
Merge branch '3.0' of github.com:cakephp/docs into 3.0
Update migration guide for HtmlHelper changes.
Update the HtmlHelper docs for most of the changes in 3.0 thus far.
Update examples, remove dead options, add missing options.
Re-order sections.

Creating buttons and closing the form happen after creating the inputs.
Cover it in the logical order people will need the methods.
Use short array syntax.
Add example of hidden attributes.
Remove data prefix.
Merge pull request #1140 from cakephp/3.0-form-5

3.0 form 5
Make indenting of sections consistent.
Reorder sections

Hopefully the new ordering makes the docs easier to follow.
Remove docs for ACL.

The code doesn't exist anymore, neither should the docs.
Fix formatting and missing anchors.
Remove lies.

Cake3 supports composite keys, so this section isn't useful anymore.
Update sections around running tests.