The space warning threshold is now configurable at runtime

The space usage threshold, at which a warning is issued, can now be configured at runtime using the EXAoperation web interface. The default value is 90%, i. e. if more than 90% of the available space on a node has been allocated (for volumes) a warning will be issued that looks similar to the following one:

[2017-03-29 08:19:29.810881] WARN: [Storage] Space usage is high on node(s): 0  (d03_storage: 98%)

Changed behavior

EXAoperation * On the page "EXAStorage" (http://localhost/cluster1/storage/index.html) the button "Background Recovery" has been renamed to "Options" * The page "EXAStorage -> Options" (http://localhost/cluster1/storage/options.html) now has the following options: ** Background Recovery Limit (same as on the original "Background Recovery" page) ** Space Warn Threshold (the new option) (+) ** Button "Force BG recovery recalibration" has been removed (-) See the attached pictures for the new UI.