fixes #268 - 500 Error on "All Puppet Classes"

Fixes #266 - Migrate the (NFS-) paths of existing Installation Media to URI format.

fixes #236 - Installation media are now usable with more than one operating system.

Fixes #265 - improved preseed template and more complicated partitioning scheme for Debian-based distributions.

fixes #264 - Overview of host's puppet classes should be sorted

Fixes #262 - Architecture selection on create/edit operating system form

Fixes #256 - Environment names should be alphanumeric

Fixes #249 - Remove AS from reports

Added a searchbar for hostname, reporting period and the type of report.

Ensure that all index views and controllers are consistent

Ensures that all controllers use @search in the index method
Ensure that all index views use pagination

Fixes #248 - Generalise tab management and search facility

The search facility is now available from all controllers.
The search bar is only displayed if there is a partial
<controller_name>/_search_line.html.erb available.This partial also
describes and implements the possible search parameters for this controller...