Upgrade go to 1.13 & Latest SDK Master

[alexanderbez]

• Targeted PR against correct branch (see CONTRIBUTING.md)

• Linked to github-issue with discussion and accepted design OR link to spec that describes this work.

• Wrote tests

• Updated relevant documentation (docs/)

• Added a relevant changelog entry to the Unreleased section in CHANGELOG.md

• Reviewed Files changed in the github PR explorer

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For Admin Use:

• Added appropriate labels to PR (ex. wip, ready-for-review, docs)
• Reviewers Assigned
• Squashed all commits, uses message "Merge PR #XYZ: [title]" (coding standards)

[alexanderbez]

Mind helping out here @fedekunze with simulation updates?

[alexanderbez]

Blocked on cosmos/cosmos-sdk#5024

[codecov-io]

Codecov Report

❗ No coverage uploaded for pull request base (master@d624ca1). Click here to learn what that means.
The diff coverage is 50%.

@@            Coverage Diff            @@
##             master     #119   +/-   ##
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  Coverage          ?   66.32%           
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  Files             ?        4           
  Lines             ?      490           
  Branches          ?        0           
=========================================
  Hits              ?      325           
  Misses            ?      134           
  Partials          ?       31