New options for 'get', 'set' and 'has'

This three methods now accept a new parameter called options.

The new available options are:
  - set
      - maxAge: Sets the maxAge for the specific entry.
              This option overrides the global maxAge
  - get:
      - maxAge: Does not return values older than maxAge.
              This option does not override the global maxAge or
              the entry maxAge.
      - stale:  Allows or disallows returning stale values per call.
              This option overrides the global stale option
  - has
      - maxAge: Does not return true for values older than maxAge.
              This option does not override the global maxAge or
              the entry maxAge