Added test cases to verify +/plus is supported in to emails

[caronc]

Description:

Related issue (if applicable): #488

To address comment added to issue above about the non-support for the '+' symbol in emails. Added test cases which appear to prove the functionality is working as proposed unless i'm overlooking something. The syntax would be any of the following:

• mailto://user:pass@domain/[email protected]
• mailto://user:pass@domain/[email protected]
• mailto://user:pass@domain/?to=Notification<[email protected]>

Testing

Anyone can help test this source code as follows:

# Create a virtual environment to work in as follows:
python3 -m venv apprise

# Change into our new directory
cd apprise

# Activate our virtual environment
source bin/activate

# Install the branch
pip install git+https://github.com/caronc/apprise.git@488-support-plus-char-in-to-email

# Test out the changes with the following command:
apprise -t "Test Title" -b "Test Message" \
  "mailto://user:pass@domain/[email protected]"

[codecov-commenter]

Codecov Report

Base: 100.00% // Head: 100.00% // No change to project coverage 👍

Coverage data is based on head (5f0e9e4) compared to base (5f0e9e4).
Patch has no changes to coverable lines.

❗ Current head 5f0e9e4 differs from pull request most recent head dc11100. Consider uploading reports for the commit dc11100 to get more accurate results

Additional details and impacted files

@@            Coverage Diff            @@
##            master      #779   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          116       116           
  Lines        14945     14945           
  Branches      3052      3052           
=========================================
  Hits         14945     14945           

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