Defined SearchActivity tab names into strings.xml file(#2136)

[cypherop]

Fixes #2136 SearchActivity tab names are hardcoded

SearchActivity has the tab names ("MEDIA" and "CATEGORIES") hardcoded.I defined these names into strings.xml file.

[domdomegg]

Don't feel names explain correctly what these strings represent. You're not really searching for media by category, more like searching for categories?

Maybe something like search_tab_title_media and search_tab_title_categories?

[cypherop]

done

[domdomegg]

Rebasing to fix Travis issues so it provides accurate result before merge...

[codecov-io]

Codecov Report

Merging #2137 into master will not change coverage.
The diff coverage is 0%.

@@          Coverage Diff           @@
##           master   #2137   +/-   ##
======================================
  Coverage    5.53%   5.53%           
======================================
  Files         233     233           
  Lines       11586   11586           
  Branches     1078    1078           
======================================
  Hits          641     641           
  Misses      10892   10892           
  Partials       53      53

Impacted Files	Coverage Δ
...va/fr/free/nrw/commons/explore/SearchActivity.java	0% <0%> (ø)	⬆️

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