Unit test development.

Unit test development.
1. CSR update(update for new specification)
2. CSR unit test update for new specification.
3. Code refactoring.
4. Update CRL pubdatatype and express RCSN as Arralist of Strings
   as in specification.
5. Fix issues for CRL table, add new unit tests, add docs for
   CertificateConstants, CertificateManager, CertificateStorage.
6. Fix issue with subjectDN and issuerDN for CA certificate and for personal one.
   please remove cloud/account/keystore folder
7. Fix last update CRL issue.
8. Fix issuer name for CRL.
9. Fix issue with basic-constraints. Code refactoring.
10. Fix issue with CRL re-creation after account restart.
11. Fix issue with CRL subject name.
12. Replace Base64 to Der coding for CRL GET. Code refactoring.
13. Put CRL to db as BinaryData and remove CRL file.
14. Add new unit tests for CRL.
15. Add new unit tests for CSR and add documentation.

Change-Id: Iadef163d6cde2ca671b70a0cc05d9a73cbf9b8a3
Signed-off-by: Andrii Androsov <a.androsov@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/10977
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Jee Hyeok Kim <jihyeok13.kim@samsung.com>