Tag Missings.jl v0.3.1

[attobot]

Repository: JuliaData/Missings.jl
Release: v0.3.1
Travis:
Diff: vs v0.3.0
requires vs v0.3.0:

--- 0.3.0/requires
+++ 0.3.1/requires
@@ -1 +1 @@
-julia 1.0-
+julia 0.7

cc: @nalimilan

Please make sure that:

• CI passes for supported Julia versions (if applicable).
• Version bounds reflect minimum requirements.

[quinnj]

@andreasnoack, do you know why METADATA is trying to test this PR on 0.6 even though the requires is for 0.7?

[andreasnoack]

For simplicity, Travis runs on all versions but doesn't really test any changes when the version isn't supported. In this case, the worker failed for other reasons before it could exit. I've restarted it.