Added knockout.rx definitions

RxJS-Knockout binding <https://github.com/Igorbek/knockout.rx>
Removed read and write functions from subscribable

read/write defined only in observable and computed
knockout.rx: added toObservableWithReplyLatest
Added description for the knockout.rx definition
Merge branch 'knockout.rx'
knockout.rx: Added TS compiler parameters for tests
knockout.rx: Added TS compiler parameters for typing
knockout.rx: fixed TS compiler parameters filename
Merge pull request #1203 from Igorbek/master

Minor changes in knockout; Added knockout.rx definitions