Renamed "Date of admission" concept

[llvasconcellos]

Renamed "Date of admission to Ebola Treatment Unit (ETU)" concept to just "Date of admission" (more generic).

This fixes #23.

[capnfabs]

Thanks for looking into this Leonardo!

I think the intention of @zestyping's comment that you quoted in projectbuendia/client#23 was to use the more generic concept instead of simply renaming it. The idea with concepts is that they're standardized across implementations, so using a standard concept makes the data more interoperable.

[dancunningham]

We should probably use 1640 - ADMISSION DATE-TIME http://dev.projectbuendia.org:9000/openmrs/dictionary/concept.htm?conceptId=1640

[dancunningham]

162622 is already incorporated into the main global CIEL concept dictionary, so we shouldn't just rename it: http://www.maternalconceptlab.com/search.php?q=id:162622&source=openmrs