refactor. cleanup
defined View should have its own inner Binder

SpecializedView::Binder is a holder for hook methods for binder.set
subclassed view with inner binder should access it with set
hooks for Binder.set before, set, after

- before does work before seting
- set overwrites the default set
- after does work after setting
binder hooks for set and value

- before_
- before_set_
- before_value_
- set_
- value_
- after_set_
- after_value_
- after_
all the template methods are hooks to inject some code that runs while calling binder.set or binder.value
set and value both use inner Binder class if view has one
getting value from view.value for pageobject that's option selectable
implemented view methods for :set, :value, :options with hooks

 before and after key hooks are always called
 before_set and after_set called from view.set
 before_value and after_value called from view.value
 before_options adn after_options called from view.options
 set, value, options methods hijack default way and you can provide custom handler
skeletal readme

stuck on what to write. all classes are documented.
review comments
set appends by default for multiselect elements

fix comments and add test example
Merge pull request #3 from Automata/binder_hooks

Binder hooks
Merge branch 'master' into wip
bump to v0.5.0 Binder has hooks for set, value, options
span element returns its text when asked for value as pageobject
remove class binder class
binder classmethod creates inner Binder class for the view
Merge pull request #5 from Automata/binder_class

view binder class method creates custom Binder for the current view
binder expects pageobject to be present when payload is used
@key and @value for current pageobject being acted on