Move Net::LDAP::PDU parsing to Net::LDAP::Connection#read

Adds instrumenting of the parsed PDU.
Remove Net::LDAP::PDU parsing calls replaced by new read behavior
Add unit test for parse_pdu.net_ldap_connection event
Refactor/cleanup read error handling
Merge branch 'master' into instrument-messages
Merge branch 'master' into instrument-messages
Add integration test for adding a person entry
Add delete integration test
Merge branch 'master' into instrument-messages

Conflicts:
	lib/net/ldap/connection.rb
Merge pull request #131 from ruby-ldap/instrument-messages

Parse Net::LDAP::PDU when calling Net::LDAP::Connection#read, instrument PDU parsing