XDCR should use "." operator for delimiting scope and collection names

XDCR collections mapping rules uses a colon for a delimiter between scope and collection names. This is inconsistent w.r.t. the usability across other Couchbase services, such as N1QL, and can cause confusion when users are setting up migration rules in the XDCR UI, which requires manual entry and the unnatural use of the ":" delimiter.

XDCR will address this by changing the delimiter from the semicolon to the dot operator. However, this change will require other components to be aware. There will need to be coordination effort across the components to ensure non-breakage when this is changed.

XDCR will prepare a functional changelist first. Once ready, I will create subtasks under this MB for each dependent component. Each component can then checkout the XDCR gerrit changelist to validate the changes. Once all the components are ready with their changesets, we can all initialize the check-in "dominos" for all the components.