Improve wording of Program Search in Cohort Builder to be more intuitive

The UI is confusing (and limited) when building a cohort based on the patient's program enrollment. Under the "When?" section, I recommend changing to the following...

(optional) In the program [this date [date|On-or-after]], [this date|On-or-before][date]]
    (optional) Enrolled in the program [this date [date|On-or-after]], [this date|On-or-before][date]]
    (optional) Completed the program [this date [date|On-or-after]], [this date|On-or-before][date]]  

I recommend we use the [on-or-after/before] terminology to match the Drug Order section of Cohort Builder, and to be very clear. If we use the terminology [between], a question remains if the cohort will include those dates; AKA >= or >

We could also consider changing the "When?" to "Date range?" to match the way dates are requested for Concepts/Observations and Regimens. Although "When?" is perfectly clear.

See the previous ticket for background...
http://dev.openmrs.org/ticket/1110

File to change is cohortBuilder.jsp
Need to also localize this text.