Add support for namespaced input classes
get right input class when inheriting form builders

* this unfortunately does not work on Ruby 1.8
  when cache_classes is on
extract class finding logic to own class
allow creation of custom actions
temporarily pass caller to deprecation messages
replace deprecated mock with double
fix one internal test of caching input classes in builder
split ClassFinder to three classes & change API to be instance level
Use Ruby 2.1.1 on travis instead of 2.1.0
extract namespace decision to action/input finder from helper
Make Inputs and Actions namespaces configurable
Minor cleanup
Speed up resolution by choosing the finder at load time
Make Class finder API more readable, fix specs

You would expect that a Finder exposes a public .find() method,
don't you? :-).

Also, move class name definition out of the public scope.
Code documentation
Add the new options to the generator template
Whitespace & Fix typo
Create an input which generates a datalist tag

Create an input which supports http://www.w3schools.com/tags/tag_datalist.asp
Used as follows
f.input :fieldname, as: datalist, collection: ["list", "of", "items"]
collection option accepts all formats supported by rails' options_for_select
Add documentation for datalist input

Add an example in README
Fix scope of DatalistInput class
Add documentation for DatalistInput class
Minor fix for file_input documentation
Add tests for datalist input

Add tests for both kinds of collections that can be provided
Add more generic helpers in custom_macros, which can be better reused
Add datalist input to autoload list