Travis-CI tests use julia v1.3

[navidcy]

Also this PR ditches Manifest.toml file (see #35).

[coveralls]

Pull Request Test Coverage Report for Build 300

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 98.649%

---

Totals
Change from base Build 294:	0.0%
Covered Lines:	1533
Relevant Lines:	1554

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💛 - Coveralls

[codecov]

Codecov Report

Merging #37 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #37   +/-   ##
=======================================
  Coverage   98.64%   98.64%           
=======================================
  Files           6        6           
  Lines         518      518           
=======================================
  Hits          511      511           
  Misses          7        7

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