Build branch params

* Document build_parameters for Project#build_branch in README
* Add params for Project#build_branch to add revision or parallel

README.md

@@ -193,6 +193,18 @@ Build a specific branch of a project
 res = CircleCi::Project.build_branch 'username', 'reponame', 'branch'
 res.body['status'] # Not running
 res.body['build_url'] # Get url of build
+
+# Passing build parameters in the post body
+build_params = { build_parameters: { 'MY_TOKEN' => '123asd123asd' } }
+res = CircleCi::Project.build_branch 'username', 'reponame', 'branch', {}, build_params
+res.body['status'] # Not running
+res.body['build_url'] # Get url of build
+
+# Adding URL params for revision or parallel
+params = { revision: 'fda12345asdf', parallel: 2 }
+res = CircleCi::Project.build_branch 'username', 'reponame', 'branch', params
+res.body['status'] # Not running
+res.body['build_url'] # Get url of build
 ```
 
 Example response

lib/circleci/project.rb

@@ -33,8 +33,8 @@ def self.build(username, project)
     # @param branch   [String] - Name of branch
     # @param body     [Hash] - Optional post body with build parameters
     # @return         [CircleCi::Response] - Response object
-    def self.build_branch(username, project, branch, body = {})
-      CircleCi.request("/project/#{username}/#{project}/tree/#{branch}").post(body)
+    def self.build_branch(username, project, branch, params = {}, body = {})
+      CircleCi.request("/project/#{username}/#{project}/tree/#{branch}", params).post(body)
     end
 
     ##

spec/circleci/project_spec.rb

@@ -80,7 +80,7 @@
     end
 
     context 'experimental api' do
-      let(:res) { described_class.build_branch 'mtchavez', 'circleci', 'master', 'SOME_VAR' => '123' }
+      let(:res) { described_class.build_branch 'mtchavez', 'circleci', 'master', {}, 'SOME_VAR' => '123' }
 
       it 'is verified by response' do
         expect(res).to be_instance_of(CircleCi::Response)