Try using the new travis infrastructure.
Convert testReadNexradTable into actual test.

Make the test actually check the results of parsing rather than
printing. This also reduces the amount of output in test logs.
Silence TestStructureArrayBB test.

Replace some output with some checks on offsets.
Silence more tests.
Make Travis use Unidata's Nexus repo.
Update pointer to Travis badge for 4.6.0.