changing alert to toast message

[MaximilianoCabreraP]

Description

I add toast.css file to style it.
I change all the alerts to the new "showToast" function that receives a message and a type (danger, warning and success)
At the bottom, I add the new features with manage the toasted message

Fixes #194

Type of change

Please delete options that are not relevant.

[ x ] New feature (non-breaking change)

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so that they can be reproduced.

• Test A
• Test B

Checklist:

• [ x ] My code follows the style guidelines of this project
• [ x ] I have performed a self-review of my code
• [ x ] I have commented my code, particularly in hard-to-understand areas
• [ x ] I have made corresponding changes to the documentation
• [ x ] My changes generate no new warnings
• [ x ] Any dependent changes have been merged and published in downstream modules