new sys variables: inputdir, masterdir, libdir, bindir, failsafe, update, local_libdir

Demo:

```
body common control
{
        bundlesequence => { 'main' };
}

bundle agent main
{
  vars:
      "sysvars" slist => { "inputdir", "masterdir", "libdir", "bindir", "failsafe", "update", "local_libdir" };
  reports:
      "variable sys.$(sysvars) = $(sys.$(sysvars))";
}
```

produces:

```
% cf-agent -KI -f ~/Dropbox/cf/test/test-sysvars.cf
2013-08-12T11:28:48-0400   notice: R: variable sys.inputdir = /home/tzz/.cfagent/inputs
2013-08-12T11:28:48-0400   notice: R: variable sys.masterdir = /home/tzz/.cfagent/masterfiles
2013-08-12T11:28:48-0400   notice: R: variable sys.libdir = /home/tzz/.cfagent/lib/3.6
2013-08-12T11:28:48-0400   notice: R: variable sys.bindir = /home/tzz/.cfagent/bin
2013-08-12T11:28:48-0400   notice: R: variable sys.failsafe = /home/tzz/.cfagent/failsafe.cf
2013-08-12T11:28:48-0400   notice: R: variable sys.update = /home/tzz/.cfagent/update.cf
2013-08-12T11:28:48-0400   notice: R: variable sys.local_libdir = lib/3.6

% sudo cf-agent -KI -f ~/Dropbox/cf/test/test-sysvars.cf
2013-08-12T11:28:55-0400   notice: R: variable sys.inputdir = /var/cfengine/inputs
2013-08-12T11:28:55-0400   notice: R: variable sys.masterdir = /var/cfengine/masterfiles
2013-08-12T11:28:55-0400   notice: R: variable sys.libdir = /var/cfengine/lib/3.6
2013-08-12T11:28:55-0400   notice: R: variable sys.bindir = /var/cfengine/bin
2013-08-12T11:28:55-0400   notice: R: variable sys.failsafe = /var/cfengine/failsafe.cf
2013-08-12T11:28:55-0400   notice: R: variable sys.update = /var/cfengine/update.cf
2013-08-12T11:28:55-0400   notice: R: variable sys.local_libdir = lib/3.6
```