Exceptions handling

Description

Created rough tree based structure for the possible calibpipe exceptions.

Filled method handle_exceptions in the core.calibrator class. This method should return the exit_status value to the tool which launched the calibration.

I will implement the example of proper exit_code handling in the tool in my subsequent merge request regarding new OpticalThroughput tests (Issue #152 ), where I will add this logic and appropriate tests.

Commits

• Deleted old exceptions import

• New tests for exceptions

• Exception handler method in core calibrator

• New exceptions classes

Related Issue

Closes #165 (closed)

How Has This Been Tested?

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.