Input splatting for ComposedOperation

Changes the way ComposedOperations expand the operation input. Removes
the call to Array() as it does convert everything that is representable
as an Array to an Array but according to this objects definition. :(
Version bump: v0.6.0 -> v0.7.0.pre
Specs for forwarding enumerable objects in ComposedOperations

Adds two currently failing specs that describe forwarding enumerable objects or in general objects that respond to #to_a in a ComposedOperation. The tests specify that objects of this kind should not be accidentally converted into an array while moving forward through the pipeline.
ComposedOperation input splatting

Input splatting is now only done for objects that have a natural array representation – meaning objects that respond to #to_ary
Merges feature: Improved input splatting and forwarding
Updates version: v0.7.0.pre -> v0.7.0
Release v0.7.0
Input forwarding of multiple parameters in a ComposedOperation

Adds tests for passing multiple parameters from operation to operation in an operation pipeline.