Adds a new mechanism to load providers from any gem or file path. (#263)

* Adds ability to load only providers used in config file

spec/unit/providers_spec.rb

@@ -0,0 +1,51 @@
+require 'spec_helper'
+require 'vmpooler/providers'
+
+describe 'providers' do
+
+  let(:providers) do
+    Vmpooler::Providers.new
+  end
+
+  it '#correct class' do
+    expect(providers).to be_a Vmpooler::Providers
+  end
+
+  it '#load_all_providers' do
+    p = [
+        File.join(project_root_dir, 'lib', 'vmpooler', 'providers', 'base.rb'),
+        File.join(project_root_dir, 'lib', 'vmpooler', 'providers', 'dummy.rb'),
+        File.join(project_root_dir, 'lib', 'vmpooler', 'providers', 'vsphere.rb')
+    ]
+    expect(Vmpooler::Providers.load_all_providers).to eq(p)
+  end
+
+  it '#installed_providers' do
+    expect(Vmpooler::Providers.installed_providers).to eq(['vmpooler'])
+  end
+
+  it '#vmpooler_provider_gem_list' do
+    expect(providers.vmpooler_provider_gem_list).to be_a Array
+    expect(providers.vmpooler_provider_gem_list.first).to be_a Gem::Specification
+  end
+
+  it '#load_by_name' do
+    expect(Vmpooler::Providers.load_by_name('vsphere')).to eq([File.join(project_root_dir, 'lib', 'vmpooler', 'providers', 'vsphere.rb')])
+  end
+
+  it '#load only vpshere' do
+    expect(providers.load_from_gems('vsphere')).to eq([File.join(project_root_dir, 'lib', 'vmpooler', 'providers', 'vsphere.rb')])
+  end
+
+  it '#load all providers from gems' do
+    p = [
+        File.join(project_root_dir, 'lib', 'vmpooler', 'providers', 'base.rb'),
+        File.join(project_root_dir, 'lib', 'vmpooler', 'providers', 'dummy.rb'),
+        File.join(project_root_dir, 'lib', 'vmpooler', 'providers', 'vsphere.rb')
+    ]
+    expect(providers.load_from_gems).to eq(p)
+
+  end
+
+
+end