Merge pull request #52 from miniway/master

change jeromq package namespace and cleanup guide
ZContext.close doesn't have to throw an exception
Merge pull request #53 from crocket/closeable

Great!
Suppress platform dependent encoding warning

http://maven.apache.org/general.html#encoding-warning
Set the compiler version to 1.6
Merge pull request #54 from crocket/compilerVersion

Set the compiler version to 1.6
Merge pull request #55 from crocket/encoding

Suppress platform dependent encoding warning
fix a bug which unsubscribe doesn't work correctly
chapter 4 java guide