skip checks in Routes()

[adokter]

fix of issue #214, adding skip_checks and min_season_quality arguments to BirdFlowR::Routes()

[ethanplunkett]

Rather than add these arguments to Routes() let's always use skip_checks = TRUE when calling lookup_species_metadata() from Routes(). Checking for quality when building a model feels important, but the Routes()` object isn't using the S&T data at all; it's just taking the species metadata.

[adokter]

@ethanplunkett made the change you suggested