Place uploader in try/rescue block and add pass_ci_if_error flag

[thomasrockhu]

addresses #129

[codecov]

Codecov Report

Merging #137 (c1da113) into master (e0aa49e) will decrease coverage by 2.45%.
The diff coverage is 33.33%.

@@            Coverage Diff             @@
##           master     #137      +/-   ##
==========================================
- Coverage   91.91%   89.46%   -2.46%     
==========================================
  Files           3        3              
  Lines         371      389      +18     
==========================================
+ Hits          341      348       +7     
- Misses         30       41      +11     

Impacted Files	Coverage Δ
lib/codecov/uploader.rb	88.58% <33.33%> (-2.72%)	⬇️
lib/codecov/formatter.rb	92.59% <0.00%> (-1.41%)	⬇️

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[LocoDelAssembly]

Should this actually be Codecov.pass_ci_if_error? (And implement the attribute)

$ rails c
Loading development environment (Rails 6.0.3.5)
irb: warn: can't alias context from irb_context.
2.7.2 :001 >   require 'simplecov'
 => true 
2.7.2 :002 >   SimpleCov.start
 => nil 
2.7.2 :003 > 
2.7.2 :004 >   require 'codecov'
 => true 
2.7.2 :005 >   SimpleCov.formatter = SimpleCov::Formatter::Codecov
 => SimpleCov::Formatter::Codecov 
2.7.2 :006 >   SimpleCov.pass_ci_if_error = true
Traceback (most recent call last):
        1: from (irb):6
NoMethodError (undefined method `pass_ci_if_error=' for SimpleCov:Module)

[thomasrockhu]

Yes, this is clearly my fault. I'll be looking to release 0.5.1 with this PR