LPS-47465 Add Factory skeleton to ease the creation of
ServiceTrackerMaps

The factory also includes mappers and comparators of general use.
LPS-47465 Added a general use mapper that simply emits the content of a
ServiceReference property passed as parameter.
LPS-47465 Add general use comparator that sorts items using a
ServiceReference property. The higher the value of the property the
higher the precedence the item will have and the earlier it will appear
on lists.
LPS-47465 Added helper methods to create both maps holding
simple objects and lists using the content of a ServiceReference
property as key. Services that do not come with the property set will
not appear in the map, since we set the filter to "("+property+"=*)"

The factory configures the maps to use property 'service.ranking' (in
case it exists) to prioritize the components.
LPS-47465 Add more convenience methods with sensible defaults.

These methods allow to create both Object and List ServiceTrackerMaps
specifying custom mappers and/or comparators. Alas not all combinations
can be properly enclosed in a factory and this will likely be a
candidate for a builder in the future but, for the moment, it is
sufficiently handy to have this factory.
LPS-47465 SF
LPS-47465 Even we are in Java 7 oficially, we still are not using all the new constructions
LPS-47465 SF
LPS-47465 Naming the exception variable with the proper name
LPS-47465 Longer name for more accuracy, even though it is a bit ugly
LPS-47465 SF
LPS-47465 Match ServiceReference
LPS-47465 Simplify by removing weird code
LPS-47465 avoid classcastexception
LPS-47465 Simplify by removing weird code
LPS-47465 It uses the property key, but then gets the property value to do something
LPS-47465 SF
LPS-47465 SF
Temp disable SFormatter for java terms since it breaks registry-api