RESTWS-646:Optimize fetching all Concepts via Rest-WS

[sherrif10]

https://issues.openmrs.org/browse/RESTWS-646
This work is in progress , cc @dkayiwa @ibacher @mks-d @k-joseph kindly review and advise will be highly welcome, Another thing can be information from the reporter unfortunately he is currently off and we are not sure whether he is still blocked or not.
WHAT I DID
1 Upgraded the openmrversion from 1.9.10 to 1.11.6 for testing purposes.
2. Tried to use some a single loop and stringbuilder in conceptResource to optmize, like i said this is WIP

[sherrif10]

I cant tell why the travis is failing, it doesnt show the logs with error problem, Am seeing the error could have arose from tests but still cant figure out with class is affected. cc

[ibacher]

@sherrif10 The test error looks a bit weird. But let me give you some pointers on this PR instead.

We don't want to change the support OpenMRS version. This could easily be why the test failure occurs, because the test is written against OpenMRS 1.8 and doesn't work on 1.11.

To implement this specific change, don't make any changes to the 1.8 version of the resource, but instead add this doGetAll() method to the ConceptResource1_11 in the omod-1.11 submodule (which already depends on OpenMRS 1.11). Then simply change the @Resource annotation on the ConceptResource1_8 class to indicate that it supports OpenMRS 1.8 only and modify the ConceptResource1_11 to support the rest of the OpenMRS versions up to 2.4.