Added username into import example

See subject
Merge pull request #35 from alefattorini/patch-14

Added username into import example
Update accounts.rst

Added username into import example
Developer manual: update events chapter
migration: create /var/lib/migration directory.
Developer manual: add DNS chapter
Developer manual: add DHCP chapter.
Developer manual: update pki chapter
Developer manual: update log rotation chapter
Developer manual: update dhcp chapter
Admin manual (it/en): refactor dns and dhcp chapters
Developer manual: add POP3 proxy chapter
Developer manual: really add POP3 proxy chapter
Admin manual (en/it): add pop3 proxy chapter
Admin manual (enterprise): update with new chapters
Devel and admin manual: update network service chapter. Refs #2895
Devel and admin manual: add pop3_connector chapter.
Admin manual (it): update mail chapter
Admin manual (en/it): update mail chapter
Developer manual: add mail chapters