1. A system for enabling multi-tenancy for a Software as a Service (SaaS) application, the system comprising: a processor; a tenant-context module, configured to (i) identify a tenant responsive to a request for the SaaS application by the tenant and (ii) identify during run-time of the SaaS application, a tenant context including a context description, wherein the context description defines software functionality required by the tenant at one or more layers of a software architecture; a policy configuration module, configured to define a plurality of policy configuration files for each tenant, the plurality of policy configuration files for each tenant defining a plurality of variations applicable at one or more variation points in the software architecture, wherein one or more of said plurality of variations are implementable for configuring the SaaS application to achieve software functionality requirements defined within an identified tenant context for a tenant to which said plurality of policy configuration files corresponds; a variation resolver module, configured to select from among the plurality of variations corresponding to a tenant identified by the tenant context module, one or more variations required to configure the SaaS application to achieve the required software functionality defined by the context description corresponding to such tenant, and further configured to apply the selected one or more variations to corresponding one or more variation points in the software architecture; and a foundation module configured to provide underlying architectural strategies to enable the identified one or more variations.