CSV serialize

[vlad-bm]

Adding class for serializing records into CSV format.

[ntarocco]

Good job! 👍 Please have a look to Travis too that is failing!

[ntarocco]

@vladbmihaescu @egabancho @slint optimized the code with in memory buffer for the CSV output and return a generator. It should be more efficient with large amount of results. Added tests.
I have tested with a REST client and it looks working fine.

[slint]

Besides the "implementation aesthetics" comment, LGTM 👍

[slint]

TBH, I prefer the second solution from this SO thread (the one with the Line class), it looks a bit higher-level (i.e. no .seek and .truncate calls)

[ntarocco]

You are right, this is much better! Will change that! 👍

[lnielsen]

I must admit I find it more intuitive to specify what to include instead of what to exclude, but that's my personal opinion. I.e. either you include all if the user didn't specify anything, or you include just what the user specfied.

[lnielsen]

Please also add tests with unicode characters (this is usually how I break the Python csv module) and check the import into e.g. Excel or other spreadsheet to ensure it loads nicely by default.

[lnielsen]

Btw, please also ensure you add it to the documentation:
https://github.com/inveniosoftware/invenio-records-rest/blob/master/docs/api.rst

[ntarocco]

Please also add tests with unicode characters (this is usually how I break the Python csv module) and check the import into e.g. Excel or other spreadsheet to ensure it loads nicely by default.

actually my fault about this, I asked him to do it previously, he did it and then I pushed again removing that by mistake :) @vladbmihaescu sorry!