Update shellcheck and shfmt to the latest version.
Fixes <https://github.com/koreader/koreader/issues/5152>.
Btw, you can apply shellcheck suggestions with a command like:
```
shellcheck --include=SC2250 -f diff *.sh | git apply
```
Apply junit testcase time fix so CircleCI can actually do something useful
with the results. This can be removed once there is a busted 2.0.rc13 or final
See 830f175c57
The debug output from Coveralls was rubbish. `"Build processing error"`
Besides some basics like checking if we were actually sending
valid JSON that gives us absolutely nothing to work with.
* Travis: speed up by caching base and running luacheck earlier
* ignore bin and install for git status change detection
* skip coverage except on official master branch. It adds 3 whole minutes and does nothing to prevent regressions
* also cache ~/.luarocks. It evens out but would generally prevent remote timeout shenenigans
* remove base cache dir before caching with verbose remove to see what's going on
* more inclusive shell code quality analysis
* fixed more shellcheck issues
* better shellcheck/shfmt debugging info
