Update to phpPgAdmin 5.1

Changes in version 5.1:

Features
* Full support for PostgreSQL 9.1 and 9.2
* New plugin architecture, including addition of several new hooks
* Support nested groups of servers
* Expanded test coverage in Selenium test suite
* Highlight referencing fields on hovering Foriegn Key values
  when browsing tables
* Simplified translation system implementation
* Don't show cancel/kill options in process page to non-superusers
* Add download ability from the History window
* User queries now paginate by default

Bugs
* Fix several bugs with bytea support, including possible data
  corruption bugs when updating rows that have bytea fields
* Numeruous fixes for running under PHP Strict Standards
* Fix navigation links when browsing results from a report
* Fix multiple bugs related to GPC parameters pollution from code
* Fix an issue with autocompletion of text based Foreign Keys
* Fix a bug when browsing tables with no unique key
* Fix a bug with nested groups when no server was set

Translations
* Lithuanian

Incompatabilities
* We have stopped testing against Postgres versions < 8.4
* phpPgAdmin core is now UTF-8 only

(asau)