[3601] Added methods to VersionedCSVFile for tracking when updating is needed

[3601] Added methods to VersionedCSVFile for tracking when updating is needed

src/lib/util/csv_file.h
    Made recreate() virtual

src/lib/util/versioned_csv_file.h
src/lib/util/versioned_csv_file.cc
    Added several methods to VersionedCSVFile:

    getValidColumnCount() - returns number of valid columns in header

    recreate() - wraps base class method, ensuring valid column
    count gets set to number of defined columns for new files

    needsUpgrading() - returns bool true if file schema is out of date

    getInputSchemaVersion() - returns schema version found in file

    getSchemaVersion() - returns current schema version

    getVersionedColumn() - returns the column definition for a given index

src/lib/util/tests/versioned_csv_file_unittest.cc
    Added checks for new methods to existing tests