Modify Signup input and validation rules

[3zcurdia]

Changelog

Given the SignUp View modify it so it can:

• Change the username to email input, consider the keyboard must be appropriated for email
• Add the following validation for password
  • At least one UperCase
  • At least one LowerCase
  • At least one symbol
  • At least one number
  • At least 8 character

Bonus:

Instead of the classic password validation implement the zxcvbn from dropbox inspired by xkcd