Added integer type massaging to NewNode

- Removed int64 casts that are now handled by integer type massaging
- Added tests for node.go
- Restructured parser_test.go and improved coverage

[#69754064]

Signed-off-by: Michael Fraenkel <fraenkel@us.ibm.com>
Moved go get of test dependencies

- Removed goveralls dependency
- Moved cover dependency checkout to use local GOPATH version if it exists,
  otherwise checks out the latest to the local GOPATH

[#69754064]

Signed-off-by: Michael Fraenkel <fraenkel@us.ibm.com>