Return scale_value as ratio (or radians)

The scale_value used to check residual observations should always
be in radians. It is a ratio, not an angle, so converting it to
degrees never made sense. Also, the SpreadsheetAbsolutesFactory
needed to NOT change the scale_value read from spreadsheets into
degrees. Finally, both the SpreadsheetAbsolutesFactory and the
SpreadsheetSummaryFactory were modified to look for spreadsheet
files more aggressively in their respective base_directories...
this was done in this commit in order to get the residual_test.py
unit tests to all pass. The only changes made to the latter were
to remove a couple of forgotten print() statements.