[ft] Dialogue box with email address text box while sending email invoice

[vrlk]

• When someone hits the email button, a pop up dialogue box should open with a text box filled with email address already get from the customer information.
• Email address text box should be editable.
• And put a send button which trigger the action of sending the mail.
• When customer information doesn't have the email address, then the pop up box should appear and user can feed the email manually and click the send button.

[vrlk]

1. in case if customer's email address is not already recorded, and putting it runtime, save it against the customer's records.
2. in case if customer's email address is already there, and I am setting new address runtime, then let it update it.