dependency slf4j-simple should be in scope "provided" or "test"

[peterkittreilly]

<dependency>
  <groupId>org.slf4j</groupId>
  <artifactId>slf4j-simple</artifactId>
  <version>1.7.12</version>
</dependency>

Is in the pom, this means that when one has 'net.code-story:http:2.104' as a dependency, one has to exclude the slf4j-simple jar.

This is not the way that libraries should use slf4j: http://www.slf4j.org/manual.html

BASIC RULE Embedded components such as libraries or frameworks should not declare a dependency on any SLF4J binding but only depend on slf4j-api. When a library declares a transitive dependency on a specific binding, that binding is imposed on the end-user negating the purpose of SLF4J. Note that declaring a non-transitive dependency on a binding, for example for testing, does not affect the end-user.

This relates to #118 - let the user configure its own logger

[peterkittreilly]

Opps: I see that #23 is already tracking this problem.