Created the class to gerate forms and do form validation

I created the Form class to deal with creating forms and validating
forms.
The ideia of this class is that other classes created by the user
could extend her and build a form in a easy way.

A user could create a form class and just specify the tags that his
form would contain along with attributes and other validation rules
without much effort.

By now the class is not complete, it only have some methods to grab
the information the user defined and transform that information in
html code.

The system/libraries/form.php is the Form class, in this class we got
the method's to do validation and parse the user information to gerate
html code.

I've also added in the config.php file a configuration that defines
what is the prefix that user forms would have. So all users form classes
names would start with Form_, and all user form classes filenames would
start with form_.

I added in the Loader class a method to load a user form, so the user
could inside the controller just type something like:

$this->load->form("myform");

And his form would be nicely loaded and added to a attribute with the
name myform and he could do something like:

if($this->myform->run() === FALSE)
    $this->load->view("form");

I created another configuration file, but just for the Form class.
In the config/form.php you could set default values for the attributes
that will be used in all forms. So if you want that all the forms have
the attribute autocomplete, then just tell your wish to the config file
and all forms would be generated with this attribute unless you tell
not to do inside a specific form.

The file form_client.php and the changes in the controller are just to
illustrate the proccess, they are not really important.
Solved some issues in the previous commit

Conflicts:
	application/controller/controller_home.php
	application/forms/form_client.php
	system/libraries/form.php