added some comments regarding the leases in the update_resource method
Changed the OLease such that the valid_from and valid_until are OProperties insted of DataMapper Properties. Corrections were made also in some of the am_manager methods and the testing files of the am_manager and the leases.
Changes tab characters to spaces.
Moved some testing files (xml requests, rb tests) to a directory called OLD_FILES
Added minitest as our new testing framework. Migrated some of the old tests we had from the rspec framework to minitest and introduced some new tests. The new tests have been placed under the directory test/am
fixed some of the minitest tests and refactored the code of the am_manager to pass those tests
Update README.md

fixed a bug in Readme.md
Introduced a new field for the leases called 'status' which can have one of the following values: 'pending', 'accepted', 'active', 'past', 'cancelled'. Refactored the code of the am_manager such that it pass the test where we don't delete the lease but we just cancell it. Finally fixed a bug in OResource file where we weren't saving the value of oproperty after we had set it.
Refactored the code of the am_manager and the authorizers such that when creating a lease, the authorizer will be asked if the caller can create a resource with type "OLease"
Modified the tests such that properties of lease objects will be treated like Time objects instead of Strings.
Simplified the properties mechanism we have. We don't keep the value in temporary variables but we save it as soon as we get a call to set the property. The previous approach is still in the comments but keeping dirty attributes gives us at least one bug. I don't see a reason why not to keep our mechanism simple and straight forward.
Modified the way we are creating leases. Lease creation is now a call to the scheduler's create_resource method. Introduced some initial tests for the scheduler and refactored its code such that it can discriminate between node and lease creation.
Refactored our Properties mechanism and added some dependencies in the gemfile
It seems that nokogiri '1.5.6' from '1.5.5' breaks the way we access attributes in XML elements. With '1.5.5' we can access an attribute like a hash value 'e.g element[:attribute]'. This doesn't work in '1.5.6'
Updated the tests regarding our properties model
Updated our resource and properties model such that it passes all the tests. We now support Time objects serialization and '<<' method in non-functional properties
Introducing a first version of the am_liaison
Added leases as sfa properties with a corresponding namespace. Attached also some leases in our initial testing resources to check how an sfa advertisement looks like.
Added lease tests
A bit of refactoring around GURN and one more lease test