update changes for 2.5.1
release 2.5.1, build 71
for #26: extract search VC from container VC
extract results disambiguation from search VC

for #27
extract search API controller from search VC
use non-deprecated restkit 0.10 methods
remove unused annotation view
disambuguator isn't a VC
warning cleanup

local variable was shadowing instance variable.
operations on observations via restkit

add comments, add ids, fetch comments & ids
clean up observation detail VC

remove unused variables, add comments to code, use ObservationsController to
make any API calls, etc.
extract search menu view from search VC
remove unneeded layout call
rename some tableview cell subclasses

for better readability
duh, view init needs super init to succceed
give the disambiguator tableview row heights

so that the cells can estimate their content view frames correctly.
no need to set disambiguation cell image height

it's implied by the margin constraints.
set ID cell content view autoresizing mask

to avoid constraint conflicts that assume the content view is 44px tall.
Merge pull request #52 from inaturalist/alex/explore-cleanup

Alex/explore cleanup