Path to julia Appveyor

[CNelias]

it seems the path to Julia has changed in Appveyor, to C:\julia\bin\julia, so the readme should be adapted accordingly.

Closes #339
Closes #328

[coveralls]

Pull Request Test Coverage Report for Build 1420933204

• 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 90.865%

---

Files with Coverage Reduction	New Missed Lines	%
src/codecovio.jl	2	87.38%
src/coveralls.jl	2	94.29%

Totals
Change from base Build 1363428186:	0.5%
Covered Lines:	189
Relevant Lines:	208

---

💛 - Coveralls

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.86%. Comparing base (453ba9f) to head (f86656d).
Report is 1 commits behind head on master.

❗ Current head f86656d differs from pull request most recent head 3d9ed4b

Please upload reports for the commit 3d9ed4b to get more accurate results.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #329      +/-   ##
==========================================
+ Coverage   90.66%   90.86%   +0.19%     
==========================================
  Files           2        2              
  Lines         225      208      -17     
==========================================
- Hits          204      189      -15     
+ Misses         21       19       -2     

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