Run CI on Julia 1.0, 1.6, v1, and nightly

[coveralls]

Pull Request Test Coverage Report for Build 934145390

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 4 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+0.5%) to 90.64%

---

Files with Coverage Reduction	New Missed Lines	%
src/codecovio.jl	2	86.87%
src/coveralls.jl	2	94.23%
<!--	Total:	4		-->

Totals
Change from base Build 934124595:	0.5%
Covered Lines:	184
Relevant Lines:	203

---

💛 - Coveralls

[codecov[bot]]

Codecov Report

Merging #320 (300dd86) into master (223e5c6) will increase coverage by 0.49%. The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #320      +/-   ##
==========================================
+ Coverage   90.14%   90.64%   +0.49%     
==========================================
  Files           2        2              
  Lines         203      203              
==========================================
+ Hits          183      184       +1     
+ Misses         20       19       -1     

Impacted Files	Coverage Δ
src/coveralls.jl	94.23% <0.00%> (-1.93%)	:arrow_down:
src/codecovio.jl	86.86% <0.00%> (+3.03%)	:arrow_up:

---

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 223e5c6...300dd86. Read the comment docs.