Added circle ci file

circle.yml

+machine:
+  java:
+    version: openjdk7
+  services:
+    - docker
+  
+general:
+  branches:
+    only:
+      - master
+          
+test:
+  override:
+    - curl -fsSL get.nextflow.io | bash
+    - ./nextflow run . 
+    
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