Update SIGNEXTEND definition and tests

Conflicts:
	libevm/VM.h
	test/vmBitwiseLogicOperationTestFiller.json
style fix

Conflicts:
	libserpent/opcodes.h
clean up PR
Update tests to new definition
style fix
Clean up
Merge pull request #432 from CJentzsch/newTests

Added tests for SIGNEXTEND and BNOT