Bundler: Fix parsing XML template output with encoding declaration

lxml 3.2.1 complains when you try to parse a unicode (in Python 2) or
string (in Python 3) containing an XML document with an encoding
declaration. Traceback:

ValueError: Unicode strings with encoding declaration are not
supported. Please use bytes input or XML fragments without
declaration.

This encodes the document as a string (in Python 2) or bytes (in
Python 3) to avoid the lxml error.  There may be other places this
happens, too, although in most other cases we should use
lxml.etree.parse() to parse a file, or we parse strings (in Python 2)
instead of unicode objects.
bcfg2-crypt: handle error when encrypting properties with multiple keys
testsuite: removed py2.5 from travis tests, no longer supported

http://about.travis-ci.org/blog/2013-11-18-upcoming-build-environment-updates/
bcfg2-admin: Restored missing "bcfg2-admin client add ... attrib=val" functionality
bcfg2-admin: added missing docstring
Core: Avoid starting server if database is enabled but cannot be used

Plugins that use the database often act quite differently depending on
whether or not the database is enabled.  If we start the server
without the database (e.g., the connection failed), then Very Strange
Things can happen.
testsuite: fixed unit tests for database fixes
testsuite: make DatabaseBacked tests work without django installed
testsuite: fixed DatabaseBacked default Core object
Tools: new Augeas driver
doc: fixed links to dynamic probe groups docs, which were moved in d8bbfbdf
testsuite: fixed Augeas unit tests in travis-ci
testsuite: install (most) optional dependencies correctly for travis-ci

Still can't get the python selinux libs to install
schemas: fixed augeasCommands group in Path entries
Encryption: fixed unit tests
POSIX: skip loading POSIX sub-tools that raise ImportError

This mimics the behavior for "real" tools
Augeas: Only install unverified commands
Augeas: Added docstrings, fixed some minor pylint issues
Augeas: avoid deprecation warning
testsuite: fixed local implementation of assertItemsEqual