CephMount.java: remove unused import

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
java libcephfs: add serialVersionUID to some Exception classes

Fix for: "The serializable class does not declare a static final
serialVersionUID field" warning.

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
Merge pull request #153 from dalgaaf/wip-da-java

Fix some small java issues