[CLJ-706] Clojure deprecation support

[arrdem]

http://dev.clojure.org/jira/browse/CLJ-706

As of Clojure 1.8, ^:deprecated metadata is completely ignored by the compiler and used mostly by tooling such as Eastwood which is less widespread than perhaps it should be. Since deprecation is an essential part of the software lifecycle, it makes sense to have language level support for deprecation warnings covering at least Clojure constructs (Vars, Namespaces).

• Warning for making use of ^:deprecated vars
• Warning for making use of ^:deprecated namespaces
• All vars in a ^:deprecated namespace are considered ^:deprecated

[arrdem]

Fixed by #2.