Handle release parameter more sensibly in force manifest.

Use release parameter to construct $release_string.

The release parameter may also be set to false to use the system's
default release (so just force a specific version). Use false as the
default setting instead of 'testing'.

Change $install_check to also check if package is installed from the
right release, instead of just checking the version.
Don't use hardcoded provider in force manifest.

Use $apt::params::provider instead.
Update specs to test all parameter cases
Update example apt::force tests
proxy support for apt::ppa
Adding specs for proxy and apt::ppa
Merge pull request #144 from hunner/ppa_proxy

Ppa proxy
ppa: fix empty environment definition in exec ressource when no proxy
Fix: apt::ppa options parameter to pass options to apt-add-repository command
Fix: ppa options support specs
Merge pull request #146 from botify-labs/handle_ppa_options

Fix: parametrize apt::ppa class for beign able to pass options to apt-add-repository command
pass flags as string of single letter
Merge pull request #148 from futuresimple/fix/ppa/pass_flags_as_single_character

pass flags as string of single letter
Merge pull request #145 from PierreGambarotto/master

ppa: fix empty environment definition in exec ressource when no proxy
Add wheezy backports support

Signed-off-by: Markus Rekkenbeil <markus@bionix-it.de>
Use the geoDNS http.debian.net instead of the main debian ftp server

Signed-off-by: Markus Rekkenbeil <markus@bionix-it.de>
Update specs for #145
Merge pull request #151 from hunner/proxy_exec_spec

Update specs for #145
Merge pull request #149 from bionix/add_wheezy_backports

Add wheezy backports support
Merge pull request #150 from bionix/use_http_debian_net_as_geodns_redirector

Use the geoDNS http.debian.net instead of the main debian ftp server