Several search fixes. Fixes #60

Register explicit search helpers to avoid respond_to?, which behaves
different in Ruby 2.0 for protected methods.

Search habtm disjunct by default, but provide the possibility for a
conjunct search.
Merge pull request #62 from hfroemmel/devel

[CSS] Changes to experts form & markdown fields. Fixes #61
Fixed strange search bug.
Merge branch 'devel' of github.com:ushis/silo into devel
Added XLSX support for list exports. Fixes #58

It is currently implemented in the AsCsv module.
Added a drop down menu to the lists export function.
Merge branch 'devel' of https://github.com/ushis/silo into devel
Added the list to excel links.