set dune version in dependent modules to 2.7

.gitlab-ci.yml

 ---
 
 include:
-  - "https://gitlab.mn.tu-dresden.de/amdis/ci-config/raw/master/config/common/releases/2.7.yml"
-  - "https://gitlab.mn.tu-dresden.de/amdis/ci-config/raw/master/jobs/common/releases/2.7.yml"
+  - "https://gitlab.mn.tu-dresden.de/amdis/ci-config/raw/master/config/common/master.yml"
+  - "https://gitlab.mn.tu-dresden.de/amdis/ci-config/raw/master/jobs/common/master.yml"
 
 before_script:
   - . /duneci/bin/duneci-init-job
-  - duneci-install-module https://gitlab.dune-project.org/core/dune-common.git
-  - duneci-install-module https://gitlab.dune-project.org/core/dune-geometry.git
-  - duneci-install-module https://gitlab.dune-project.org/staging/dune-uggrid.git
-  - duneci-install-module https://gitlab.dune-project.org/core/dune-grid.git
-  - duneci-install-module https://gitlab.dune-project.org/core/dune-istl.git
-  - duneci-install-module https://gitlab.dune-project.org/core/dune-localfunctions.git
-  - duneci-install-module https://gitlab.dune-project.org/staging/dune-typetree.git
-  - duneci-install-module https://gitlab.dune-project.org/staging/dune-functions.git
-  - duneci-install-module https://gitlab.dune-project.org/martin.nolte/dune-polygongrid
-  - duneci-install-module https://gitlab.dune-project.org/extensions/dune-alugrid.git
+  - duneci-install-module -b releases/2.7 https://gitlab.dune-project.org/core/dune-common.git
+  - duneci-install-module -b releases/2.7 https://gitlab.dune-project.org/core/dune-geometry.git
+  - duneci-install-module -b releases/2.7 https://gitlab.dune-project.org/staging/dune-uggrid.git
+  - duneci-install-module -b releases/2.7 https://gitlab.dune-project.org/core/dune-grid.git
+  - duneci-install-module -b releases/2.7 https://gitlab.dune-project.org/core/dune-istl.git
+  - duneci-install-module -b releases/2.7 https://gitlab.dune-project.org/core/dune-localfunctions.git
+  - duneci-install-module -b releases/2.7 https://gitlab.dune-project.org/staging/dune-typetree.git
+  - duneci-install-module -b releases/2.7 https://gitlab.dune-project.org/staging/dune-functions.git
+  - duneci-install-module -b master       https://gitlab.dune-project.org/martin.nolte/dune-polygongrid
+  - duneci-install-module -b releases/2.7 https://gitlab.dune-project.org/extensions/dune-alugrid.git