Fix Unit tests.

Fix Unit tests.
1) Add cleaning up for CERTIFICATE_TABLE and CRL_TABLE in Mongo.
2) Fix random test execution with help of @BeforeClass annotation in CrlResourceTest.
3) Fix SVACE issues.
4) Add new java documentation for public and private methods.

Change-Id: I43b7c2dc814d67d3a53b598f4eddf3c1acc2a94d
Signed-off-by: Andrii Androsov <a.androsov@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/12177
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: dongik Lee <dongik.lee@samsung.com>
Reviewed-by: Jee Hyeok Kim <jihyeok13.kim@samsung.com>