add Groups in build script

.travis.yml

@@ -4,7 +4,6 @@ os:
   - linux
   - osx
 julia:
-  - 0.6
   - 0.7
   - 1.0
   - nightly
@@ -15,6 +14,9 @@ matrix:
   allow_failures:
     - julia: nightly
 
+script:
+  - julia -e 'using Pkg; pkg"add https://github.com/kalmarek/Groups.jl#enh/julia-v0.7"; Pkg.build(); Pkg.test(coverage=true);'
+
 after_success:
   # push coverage results to Coveralls
    - julia -e 'import Pkg; Pkg.add("Coverage"); using Coverage; Codecov.submit(process_folder())'