Added multiple alerts compatibility for SweetAlerts2

[PauMAVA]

As discussed in issue #9 , I've implemented a way to issue multiple alerts. To do so, the user must predefine the **kwargs of every alert as a dict and then pass all of those dicts to sweetify.multiple(). Here goes an example:

args1 = dict(title='Test1', icon='info', text="Text placeholder1", button="Next")
args2 = dict(title='Test2', icon='success', text="Text placeholder2", timer=5000, timerProgressBar='true', persistent="Close")
sweetify.multiple(request, args1, args2)

The changes made are the following:

• Added function multiple(request, *args) on sweetify/sweetify.py
• Splitted funcion sweetalert(request, title,**kwargs) into sweetalert(request, title,**kwargs) and _treat_data(opts) so that part of the code present in sweetalert function can be used by both sweetalert and multiple function. (sweetify/sweetify.py)
• Added function _flash_multiple_configs(request, jsonData) to flash multiple configs correctly when using the multiple function.
• Added function concatenate(list) on sweetify/templatetags/sweetify.py. This function parses the multiple alerts config and converts it to the corresponding javacript code.
• Modified function sweetify(context) to adapt to the changes.

THIS MODIFICATION IS ONLY COMPATIBLE WITH SWEETALERTS2. If the user tries to use multiple alerts with sweetalerts1 then sweetify will not flash any javascript code.

[coveralls]

Coverage decreased (-4.9%) to 29.204% when pulling f65b177174160479753978cc78c3e005e9d91126 on PauMAVA:master into e785a7fb9fe334cc76b9fa303aa0657f9b60999b on Atrox:master.

[Atrox]

Hey @PauMAVA,

thanks for implementing this. Could you update the README with info and examples how this works?

[PauMAVA]

Hey @PauMAVA,

thanks for implementing this. Could you update the README with info and examples how this works?

Hello @Atrox,

As you requested I've modified the README.md.

[Atrox]

Thank you for the contribution @PauMAVA :)

[skatepalli1712]

I installed sweetalert version2.0 in Django framework When I try to use sweetify for multiple alerts I get this error "Attribute Error - module 'sweetify' has no attribute 'multiple' " Any help is highly appreciated