search: download search result export

[lnielsen]

Moved from inveniosoftware/invenio-search#72

request: Need an easy way to export search in a special format

Hello,

We would like if possible a system that allow an easy way to download the export of a search in a given format, thanks to the UI.

For example:

The use run a search.
Click on a button, it downloads a file ( for example the xml export of the results).

Thanks