Contract msg send tokens

[ethanfrey]

Closes #35

• 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

---

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)

[codecov-io]

Codecov Report

Merging #37 into master will increase coverage by 0.3%.
The diff coverage is 73.91%.

@@            Coverage Diff            @@
##           master      #37     +/-   ##
=========================================
+ Coverage   61.15%   61.46%   +0.3%     
=========================================
  Files          15       15             
  Lines        1089     1095      +6     
=========================================
+ Hits          666      673      +7     
+ Misses        358      356      -2     
- Partials       65       66      +1

Impacted Files	Coverage Δ
x/wasm/internal/keeper/keeper.go	67.46% <73.91%> (+2.03%)	⬆️
lcd_test/helpers.go	75.53% <0%> (-0.72%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 3efd474...e28db84. Read the comment docs.