Update Travis script

Author: timholy

.travis.yml

@@ -1,12 +1,9 @@
 language: julia
 sudo: false
 julia:
-    - 0.6
     - 0.7
+    - 1.0
     - nightly
-matrix:
-    allow_failures:
-        - julia: nightly
 after_success:
   # push coverage results to Coveralls
   - julia -e 'cd(Pkg.dir("Interpolations")); Pkg.add("Coverage"); using Coverage; Coveralls.submit(Coveralls.process_folder())'