fix errorf in marshal.go

author: @virtuallynathan
'go test' not non-verax-tests.sh

* rm non-verax-tests.sh, Travis
* separate verax directory
* disable TestGenericWalk
* update readme's
Fixed walk issue (TestGenericWalk)

The test TestGenericWalk was failing against snmpd on Ubuntu.  This was
caused by the last OID repeating with an EndOfMibView.  Reordered the
walk loop checks so the sanity checks are done after testing for
EndOfMibView.
Merge branch 'master' of https://github.com/soniah/gosnmp