Add a decorator for creating table via class-style.

[YogiLiu]

This feature add a decorator to create table via class-style, it's friendly to type hint.

from pypika import table_class, Table, Field, Query

@table_class('customers')
class Customer(Table):
    id = Field('id')
    first_name = Field('fname')
    last_name = Field('lname')
    phone = Field('phone')

q = Query.from_(Customer).select(Customer.id, Customer.first_name, Customer.last_name, Customer.phone)

The decorator's parameters are same as Table.__init__.

[AzisK]

Suggested change

	The table also can create via class-style:
	The table can also be created via class-style:

[AzisK]

Suggested change

	def test_table_with_field_and_ailas(self):
	def test_table_with_field_and_alias(self):

[AzisK]

It looks good. Thanks for your work. Could you resolve the conflicts and updater with master branch?