python: Add support for python3+

Added a --with-python=VERSION option to configure.ac, and changed the
python destination to work with both python2 and python3. Tested with
python 2.7 and 3.3.

The configure check defaults to searching for the unversioned "python"
package.

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
lua: Silence a compiler warning

Define LUA_COMPAT_MODULE in lua-utils.c, to silence a compiler warning.

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
.travis.yml: Add python & riemann dependencies

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
basicfuncs+: Fix a think-o

When parsing a number, during any of the numeric template functions, and
the parse fails, display the error message correctly. Previously, the
same error message was displayed for both the first and the second
argument, and both messages said "first argument".

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
Merge pull request #38 from algernon/h/num-parse-fixup

basicfuncs+: Fix a think-o
Merge pull request #36 from algernon/f/travis-update

.travis.yml: Add python & riemann dependencies
Merge pull request #35 from algernon/h/lua/openlib

lua: Silence a compiler warning
Merge pull request #34 from algernon/f/mod-python/py3

python: Add support for python3+
A few tests for various Incubator modules

This adds a basic test suite (based on BATS), and some trivial tests for
basicfuncs+, getent and graphite-output template functions, and the
trigger-source module.

This partially addresses #37.

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>