OPENDJ-1166-checkpoint Improve tools behavior

CR-7196
This commit fixes tools error messages when
* instance is not configured or user have insufficient access rights

* src/main/java/org/opends/server/tools/tasks/TaskTool.java
** Creates a checkVersion() method to allow better encapsulation
* src/main/java/org/opends/server/util/BuildVersion.java
** Filter IOException raised to check if the instance has been configured (i.e buildinfo file exists) and if user has sufficient priviledges to read it.
* src/messages/org/opends/messages/tool.properties
* src/main/java/org/opends/server/tools/BackUpDB.java
* src/main/java/org/opends/server/tools/ExportLDIF.java
* src/main/java/org/opends/server/tools/ImportLDIF.java
* src/main/java/org/opends/server/tools/RebuildIndex.java
* src/main/java/org/opends/server/tools/RestoreDB.java
** Consequences of changes described above