add test to catch and case sensitive files
remove Env tests since they don't define classes
rename to make consistent with others
add NAME
inherit import from Genome::Env::Required

Instead of using side effect of `use Genome::Env::Required` inherit the
import method with the requirement check.
add missing package declarations
mark many GENOME_* variables as required

If we defined a value in Genome::Site::TGI and a default_value was not
supplied then these are now "required" configuration.  A few exceptions
were:

GENOME_DEV_MODE
GENOME_STATSD_HOST
GENOME_STATSD_PORT

We can decide later whether not having these set should be a
compile-time or run-time error.  For now we have to be careful about
failing when they are not set since the code that uses them is probably
not very defensive about it.