Install Linux ARM tarball automatically

[rok-cesnovar]

Summary

Fixes #503

I didnt find a way to add a test as we dont have ARM machines to test this with so existing install tests on x86 will have to suffice. I did try it on an AWS ARM machine and it works.

Copyright and Licensing

Please list the copyright holder for the work you are submitting
(this will be you or your assignee, such as a university or company):
Rok Češnovar

By submitting this pull request, the copyright holder is agreeing to
license the submitted work under the following licenses:

• Code: BSD 3-clause (https://opensource.org/licenses/BSD-3-Clause)
• Documentation: CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/)

[codecov-commenter]

Codecov Report

Merging #531 (d96c63a) into master (19056cf) will decrease coverage by 1.17%.
The diff coverage is 88.88%.

❗ Current head d96c63a differs from pull request most recent head 849915f. Consider uploading reports for the commit 849915f to get more accurate results

@@            Coverage Diff             @@
##           master     #531      +/-   ##
==========================================
- Coverage   92.79%   91.61%   -1.18%     
==========================================
  Files          12       12              
  Lines        3041     3007      -34     
==========================================
- Hits         2822     2755      -67     
- Misses        219      252      +33     

Impacted Files	Coverage Δ
R/install.R	63.27% <88.88%> (-5.29%)	⬇️
R/run.R	94.07% <0.00%> (-1.65%)	⬇️
R/utils.R	90.71% <0.00%> (-1.43%)	⬇️
R/model.R	90.93% <0.00%> (-0.81%)	⬇️
R/csv.R	98.21% <0.00%> (-0.45%)	⬇️

---

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 19056cf...849915f. Read the comment docs.

[jgabry]

Looks ok to me!