#124 added new class SqlConnectionException

this class is used since the Conncetion interfaces enforces the delete /
insert / update metaobjects method to throw an ConnectioException. This
class is used to indicate that during an server operation a SQL has
occured. In case such a an exception is thrown, we use a custom error
dialog that is shown to the user
 #124 custom SQLException handling for RMIConnection

when an Excpetion is thrown during an insert/update/deleteMetaObject
method, check if the top level Cause if this Exception was an
SQLException. If so re-throw a SqlConnectionException which should be
handled by showing a seperate ErrorDialog, that offers more information
of the SQLException
 #124 custom SQLException handling for RESTfulConnection

when an Exception is thrown during an insert/update/delete Metaobject,
check if the top level cause was an SQLException. If so re-throw a
SqlConnectionException which enforces the visualisation of a custom
error dialog
 #124 show custom ErrorDialog for SqlConnectionException

the error dialog for SqlConnectionException also contains the
getMessage() text of the SQLException that was thrown on the server
 #124 dialogs generated with ExceptionManager are resizable
 #124 format text of messageLabel in ErrorPane

the text is inserted in an table with a fest width. this prevents that
the dialog width exceeds with large error message texts. if the text
already starts with a <html> tag, the text is inserted like it is
Merge branch 'feature/124-custom-sql-error-dialog' into dev
Merge branch 'dev' of github.com:cismet/cids-navigator into dev