Add download as CSV/XLSX to Query results + update static assets

[gdubicki]

Additionally update jQuery and other JS & CSS related to DataTables.

[codecov]

Codecov Report

Merging #654 (9585a88) into master (f3d3838) will increase coverage by 0.05%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #654      +/-   ##
==========================================
+ Coverage   82.72%   82.77%   +0.05%     
==========================================
  Files          12       12              
  Lines         897      900       +3     
==========================================
+ Hits          742      745       +3     
  Misses        155      155              

Impacted Files	Coverage Δ
puppetboard/app.py	78.36% <100.00%> (+0.11%)	⬆️

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[gdubicki]

This is how the buttons and query results in non-JSON mode will look:

[gdubicki]

This partially implements #428 and #30. Extending it to cover all the tables can be added in another PR and I would be happy if someone else would like to do it. :)

[bastelfreak]

updating the static files doe not relate to the new feature? please put that into a dedicated PR. Do you have any semiautomatic way for updating the files? If so, please document that.

[gdubicki]

updating the static files doe not relate to the new feature? please put that into a dedicated PR. Do you have any semiautomatic way for updating the files? If so, please document that.

That request makes a lot of sense and normally I would totally agree.

However as I was adding a new feature that is using a new library I have added it in the latest stable version. And to avoid compatibility issues I updated the related libraries too.

Theoretically I could downgrade Datatables Buttons to a version compatible with the version of Datatables that we had before the upgrade but I don't even know which that is - they are versioned separately and the website doesn't allow choosing older versions on their download page.

Because of that and because we didn't upgrade any major version here, I think that we can keep this change in this PR.

PS And no, sadly I don't have any automation for the libs update. I just find them on https://cdnjs.com/, get the code to put it into the templates + wget the files themselves to add them to the repo as statics.