correctly parse empty parameter values in CIB objects

For a CIB object definition such as:

    primitive database-config-default-fs ocf:heartbeat:Filesystem \
            params device="/dev/drbd/postgresql" directory="/var/lib/pgsql" fstype="" \
            op monitor interval="10s"

when #extract_hash attempts to extract the 'params' section,
Shellwords.split will return an Array whose last element is

    fstype=

not

    fstype=""

as you might expect.  Therefore we need to allow for an empty string to
the right of the equals sign, otherwise parsing fails.
add FIXMEs for full grammar parsing

@tserong will probably have to fix these if he wants to incorporate this
class hierarchy into Hawk ;-) But of course we'd first need to split it
off into a separate gem (which should be easy - I've deliberately kept
the code fairly cleanly separated).
move #crm_configure_command to Pacemaker::CIBObject
rename #crm_configure_command to #configure_command

Done for consistency with #reconfigure_command and #delete_command, and
also bearing in mind that in future it's conceivable that the
configuration command might not always use crm, or might use other
commands in conjunction with crm (c.f. #reconfigure_command).
avoid hardcoding usage of class under test

Hardcoding makes it more difficult to refactor common test code
for reuse later on.
extend Pacemaker::Constraint::Colocation tests
implement Pacemaker::Constraint::Location
remove unused variable
implement location LWRP using library code
Merge pull request #47 from aspiers/parse-empty-cib-vals

correctly parse empty parameter values in CIB objects
Merge pull request #48 from aspiers/location

add LWRP for location constraint
Merge pull request #49 from vuntz/ruby-shadow

Clear gem paths after installing ruby-shadow
Merge pull request #46 from vuntz/authkey-sync

Make sure all nodes in the cluster use the same authkey
Merge branch 'release/roxy/master' into roxy-sync

Conflicts:
	crowbar_framework/app/helpers/pacemaker_barclamp_helper.rb
	crowbar_framework/app/views/barclamp/pacemaker/_edit_attributes.html.haml