- Added new classes for listening to java.util.Map changes:
ObservableMap, MapChangeSupport, IMapChangeListener, and MapChangeEvent.
- Now requires Java 7 or higher.
- Refactored Properties to extend ObservableMap so changes can
optionally be tracked.
New ContentType class to represent a file media/MIME type and obtain its
usual name and file extension.

FileMonitor, FileUtil, IFileChangeListener, IFileVisitor are now found
under the com.norconex.commons.lang.file package.  Classes have been
deprecated in former location.
ContentType: Removed the dots from extensions and added XML content
type.
Added TEXT to ContentType and changed its get(String) method to
valueOf(String).
Removed remaining dots before some ContentType extensions.  Fixed
ContentType test.
QueryString now preserves insertion ordering.
Fixed URLNormalizer due to failing tests.
New DataUnit class to perform data unit (KB, MB, GB, etc) conversions
much like Java TimeUnit class.
New DataUnitFormatter to format any data unit ot a human-readable format
taking into account locale and decimals.
Fixed decimal precision issue.
Now returns content-types without display names in sqare brackets.
Added one more extension.
New PercentFormatter to format fraction values as percentage string.
Made serializable.
Added Office Open XML visio content types.
Added .ini to ContentType.
Added empty constructor.
Properties now uses UTF-8 to load and store itself.
Added ContentType families.
Loglevel updaate on ContentType.
Javadoc fix.
 Fix junit test for converting IP to domain.