Move the `zk` gem from a explicit gem dependency to an implicit dependency

This will give us some optionality on how we want to reach out and contact
Zookeeper across multiple environments. See #75

Gemfile

@@ -4,8 +4,13 @@ gemspec
 
 group :development do
   gem 'rake'
+  gem' ruby-maven', :platform => :java
+  gem 'jar-dependencies', :platform => :java
   gem 'rake-compiler'
   gem 'pry'
+
+  # Used for testing `zk` gem based functionality
+  gem 'zk', '~> 1.9.4'
 end
 
 group :test do

hermann.gemspec

@@ -24,14 +24,13 @@ Gem::Specification.new do |s|
   s.specification_version = 3 if s.respond_to?(:specification_version)
 
   s.add_dependency 'concurrent-ruby', '~> 0.7.0'
-  s.add_dependency "zk", "~> 1.9.4"
   s.add_dependency 'thread_safe', '~> 0.3.4'
 
   if RUBY_PLATFORM == "java"
-    #IMPORTANT: make sure that jar-dependencies is only a development dependency of your gem. if it is a runtime dependencies the require_jars file will be overwritten during installation.
+    # IMPORTANT: make sure that jar-dependencies is only a development
+    # dependency of your gem. if it is a runtime dependencies the require_jars
+    # file will be overwritten during installation.
     s.add_dependency 'jar-dependencies', '~>0.1.2'
-    s.add_development_dependency 'ruby-maven', '~> 3.1.1.0'
-    s.add_development_dependency 'rake'
     s.requirements << "jar org.apache.kafka:kafka_2.10, 0.8.1.1"
     s.requirements << "jar org.mod4j.org.eclipse.xtext:log4j, 1.2.15"
     s.requirements << "jar org.scala-lang:scala-library, 2.10.1"