Fixes related to Issue 118 - venv

[razman786]

Related to https://github.com/ska-sa/tigger/issues/118 for using the installation script in a venv.

• Added venv support
• Updated exception output for end user clarity
• Updated error exit process
• Fixed typo's
• Adjusted formatting

[ratt-priv-ci]

Can one of the admins verify this patch?

[razman786]

Closing as this has been merged into https://github.com/ska-sa/tigger/pull/114