attempt at stabilizing the Travis-CI builds

 - https://issues.scala-lang.org/browse/SI-8772
 - https://github.com/sbt/sbt/issues/1439#issuecomment-51860493
Add test for Series.++
Remove unneeded s
Add tests for Series.closestKeyTo
Improve coverage for Series.zipMap
Merge pull request #33 from mrvisser/topic/series-merge-tests

Add test for Series.++
Merge pull request #34 from mrvisser/topic/series-closestkeyto-tests

Add tests for Series.closestKeyTo
Merge branch 'master' into topic/series-foreach

* master:
  Improve coverage for Series.zipMap
  Add tests for Series.closestKeyTo
  Remove unneeded s
  Add test for Series.++
  attempt at stabilizing the Travis-CI builds

Conflicts:
	framian/src/test/scala/framian/SeriesSpec.scala
Merge pull request #1 from mrvisser/topic/series-foreach

resolve conflicts with master
Test to ensure Index sort remains stable