Refresh all the repos

[FengyunPan2]

Currently if config file have a bad repo and some right repos,
monocualr-api don't get charts from repos and no error message to
user. We should try all the repos.

[prydonius]

the error message should start with a lowercase: "error on refresh..."

[FengyunPan2]

Done

[prydonius]

This is great, thanks @FengyunPan2. Can you update the tests as these are failing because they were expecting the error:

--- FAIL: TestNewRefreshDataError (0.00s)
	assert.go:138: /go/src/github.com/kubernetes-helm/monocular/src/api/data/cache/auto_refresher_test.go:38: given error for Error executing refresh was nil when it shouldn't have been
--- FAIL: TestCachedChartsRefreshErrorPropagation (0.00s)
    --- FAIL: TestCachedChartsRefreshErrorPropagation/invalid_repo_url (0.00s)
    	assert.go:138: /go/src/github.com/kubernetes-helm/monocular/src/api/data/cache/cache_test.go:183: given error for invalid repo url was nil when it shouldn't have been
    --- FAIL: TestCachedChartsRefreshErrorPropagation/inexistant_repo (0.00s)
    	assert.go:138: /go/src/github.com/kubernetes-helm/monocular/src/api/data/cache/cache_test.go:183: given error for inexistant repo was nil when it shouldn't have been
=== RUN   TestCachedChartsRefreshErrorDownloadingPackage

[codecov-io]

Codecov Report

Merging #470 into master will decrease coverage by 0.08%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #470      +/-   ##
==========================================
- Coverage   83.86%   83.77%   -0.09%     
==========================================
  Files          26       26              
  Lines        1549     1553       +4     
==========================================
+ Hits         1299     1301       +2     
- Misses        198      199       +1     
- Partials       52       53       +1

Impacted Files	Coverage Δ
src/api/data/cache/cache.go	90.1% <100%> (+0.22%)	⬆️
src/api/data/cache/auto_refresher.go	87.5% <0%> (-12.5%)	⬇️

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[prydonius]

lgtm!