introduce a workaround for multiple units for the same observedProperty
add convenience method for creating inner joins
add unit to procedure query; only output procedures that have data
only return those networks that contain observations
introduce a cache component for Observation Offerings
some logging statements regarding caching
schedule cache update at midnight
implement a mechanism to lock cache updates
Add a property to disable cache updates on startup
build up the cache if it is not already there on request.
include check for size limit on GetFOI. if exceeds, throw exception.
Merge pull request #51 from matthesrieke/master

integrate latest developments