added github pr plugin

Author: nick-codefresh

incubator/github-pr/README.MD

@@ -0,0 +1,10 @@
+# GitHub Pull Request Codefresh Plugin
+
+Creates a new pull request in GitHub
+
+## Environment Variables
+
+- `GITHUB_TOKEN`: token for access to GitHub
+- `HEAD`: The name of the branch where your changes are implemented. For cross-repository pull requests in the same network, namespace head with a user like this: username:branch
+- `BASE`: The name of the branch you want the changes pulled into. This should be an existing branch on the current repository. You cannot submit a pull request to one repository that requests a merge to a base of another repository.
+- `TITLE`: The title of the pull request

incubator/github-pr/plugin.yaml

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+image: codefresh/github-pull-request
+tag: master
+version: 0.1.0
+description: Creates GitHub pull request
+keywords:
+  - docker
+  - github
+  - pull-request
+home: https://github.com/codefresh-io/cf-github-pull-request
+sources:
+  - https://github.com/codefresh-io/cf-github-pull-request
+maintainers: # (optional)
+  - name: Nick Sakovich
+    email: [email protected]
+icon: https://assets-cdn.github.com/images/modules/logos_page/GitHub-Mark.png
+envs:
+  - name: GITHUB_TOKEN
+    type: required
+    description: Token for access to GitHub
+  - name: HEAD
+    type: required
+    description: The name of the branch where your changes are implemented. For cross-repository pull requests in the same network, namespace head with a user like this: username:branch
+  - name: BASE
+    type: required
+    description: The name of the branch you want the changes pulled into. This should be an existing branch on the current repository. You cannot submit a pull request to one repository that requests a merge to a base of another repository.
+  - name: TITLE
+    type: required
+    description: The title of the pull request