Add javadocs to DeviceType
a few cleanups in the code.
Update javadocs

[ci skip]
pub/sub work.
Merge branch 'zeromq-master'

Conflicts:
	src/main/java/org/zeromq/api/Context.java
	src/main/java/org/zeromq/api/Receivable.java
	src/main/java/org/zeromq/api/Socket.java
updated code to latest from the origin repo.
cleaned up redundant variable.
Merge pull request #1 from jkwatson/master

A few little cleanups in the code
Add John Watson as a contributor

[ci skip]
Add transport type to Socket
Remove throwing exceptions from Receivable and Sendable and it's variants.

This is to avoid having to try catch everywhere and to put off the decision
about what the API looks like to later time.