System Test Loading and Data Integrity Base

[OwenArnold]

Would be useful to have a base class that took away the need to write basic data loading and data integrity checks.

I'm thinking about this from the point of view of reflectometry, where some of the instruments don't use Mantid, so the only things we want to do are:

• Load a raw file
• Load the equivalent nexus file
• Compare the shape of the data in the raw workspace and nexus workspace
• Integrate out the data in one of the workspaces (or just one period if multi-period). This should make comparison workspaces smaller and allow check workspaces match to run quicker.
• Run a comparison against the reference result.

[OwenArnold]

This issue was originally trac ticket 5598