package_server: Refs #2214 Add adobe reader support
package_server: Refs #2213 replace twisted Agent class

Current package-server code use Twisted 9 code and RHEL6 comes with 8.2.

twisted.web.client.Agent class can't be used in twisted < 9.

So, use twisted.web.client.getPage method to do the job
imaging: Refs #2191 Traceback when associate imaging

When associating imaging server with other entity than UUID1 (who comes
with imaging SQL schemas), english default language cannot be set.

And a traceback is born...

This commit fixes it
imaging: Refs #2207 Drop table ImagingLogLevel

When restoring master, imaging tries to log a message with a non
existing level (level 9).

ImagingLogLevel table is useless (storing log levels) => dropped
inventory: Refs #2201 remove base.ini dependency

Inventory server can be installed stand-alone where there is no
/etc/mmc/plugins/base.ini file

This base.ini was used to get ldap root password for some method
authentication.

So, I remove ldap authentication for these methods:

glpi.getMachineUUIDByMacAddress
glpi.hasKnownOS