Add config template for s3 usage

s3-test.config.template

+params {
+  // replace <mybucket> with your own bucket
+  input = 's3://<mybucket>/data/*.fastq.gz'
+  output = 's3://<mybucket>/results/'
+}
+aws {
+   // replace <accessKey> and <secretKey> with your keys
+   // you may also consider adding this whole scope into your global nextflow config
+   // in $HOME/.nextflow/config
+   accessKey = '<accessKey>'
+   secretKey = '<secretKey>'
+   client {
+      endpoint = 'https://s3.computational.bio.uni-giessen.de'
+   }
+}