Since the merge of I26f5bcd784 the ability to use OAUTH for WebUX and
Gerrit HTTP auth for Git/REST API has been lost.
That was a useful use-case when people needed to use a random password
for batch operations using Git/HTTP or for REST API processing.
By using the same technique experimented for LDAP/HTTP authentication
it is possible to choose if Git/HTTP and REST need to be validated
against OAUTH or using the Gerrit's hashed HTTP password.
Change-Id: I1fbabc3fa11ae0cb98308592e1be09039be78ff5
51edcb7755