Moving from Julia 1.0 to Julia 1.3

Reasons:

BlockArrays requires at least Julia 1.1
5 argument mul! requires Julia 1.3

We could find a workaround for mul! so that we could use Julia 1.1.
But I don't believe it is worth the effort since Julia 1.0 is dead and
the next LTS version will be 1.6 (announced by S. Karpinski at
JuliaCon 2020).

Author: fverdugo

.travis.yml

@@ -9,8 +9,8 @@ language: julia
 os:
   - linux
 julia:
-  - 1.0
-  - 1.4
+  - 1.3
+  - 1.5
 notifications:
   email:
     on_success: never