added EthernetFrame again as it turned out it's possible to send
arbitrary data over a raw socket. Also added the unit test again.
Merge remote-tracking branch 'origin/master'

Conflicts:
	build.gradle
	src/main/aspectj/at/fabianachammer/nsend/aspect/PreConditionValidation.aj
	src/main/java/at/fabianachammer/nsend/NSender.java
	src/main/java/at/fabianachammer/nsend/pdu/EthernetFrame.java
	src/test/java/at/fabianachammer/nsend/aspect/PreConditionValidationTest.java
	src/test/java/at/fabianachammer/nsend/pdu/EthernetFrameTest.java