Logging library dependancy required.

[PaulSchulz]

When initially trying to get the library to work (as per instructions) I got the following error:

user=> (use 'bitcoin.core)
SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.

Adding the following to project.clj allowed removed the error:

[org.clojure/tools.logging "0.3.1"]
; No need to specify slf4j-api, its require d by logback
[ch.qos.logback/logback-classic "1.1.3"]

See:

• http://www.slf4j.org/codes.html#StaticLoggerBinder
• https://spin.atomicobject.com/2015/05/11/clojure-logging/