Bug fix for issue 630 Router checks for selected variant before defaulting to req params.

- fix few typos here and there;

- `cartTransform` methods refactored;
- added `getSummary` function;

- `products/updateVariants` removed. It is were
replaced by new `products/updateVariantsPosition`
method;

- variant sorting reworked;

- `schema.productVariant.index` from now will keep
the top-level variant list index;

- fix all broken tests. Added few new tests,
and removed few unnecessary tests;

- removed a lot of `this.unblock()`, because I think
this is not needed, maybe even bad for our cases;

- `minOrderQuantity` field added to productVariant
 schema, due to reactioncommerce#225;

- added `flushQuantity` function to update to zero
top-level variant quantity.

- added `getVariantQuantity` common function,
and the same called template method, which returns
the summary of all options if their exists;
- added `denormalize` function;
- added `isSoldOut` function;
- added `isLowQuantity` function;
- added `isBackorder` function;
All this new function is useful for denormalizing of
productVariant SS fields;

- `inventory/register`, `adjust` updated.
Implemented `initializeUnorderedBulkOp()` instead of
`batchInsert`;

- A lot of UI updates due to compatability with flattened model;

- revert changes from reactioncommerce#632;

- products fixture modified;

- `shopIdAutoValue` method modified. Now it is ignore
update operations;