Respect collection order

This pull request solves issue #131.

Implemented reordering of destination collection according to source one. By default old behavior is used.
Implemented UseSourceOrder option for mapping configuration expression.
Added test to check collection reordering.
Additionally refactored src/AutoMapper.Collection.Tests/MapCollectionWithEqualityTests.cs to check that nothing is broken in both UseSourceOrder(true) & UseSourceOrder(false) cases.

AutoMapper / AutoMapper.Collection