Using class method swizzling to dynamically modify class method values for acceptable status codes and content types
Adding documentation for AFHTTPRequestOperation +addAcceptableStatusCodes / +addAcceptableContentTypes
Adding new documentation header for AFHTTPClient +canProcessRequest
Adding AFContentTypesFromHTTPHeader()
Refactoring +canProcessRequest: and content type acceptability
Removing unused overrided implementation of  HTTPRequestOperationWithRequest:success:failure: in AFImageRequestOperation
Added additional Reachability information to the AFHTTPClient

As discussed by @mattt in #197, this pull request takes a stab at
exposing the Reachability state via an enum property, similar to
Reachability itself.
Changed AFReachabilityStatus naming scheme to be more clear
Merge branch 'AFHTTPClient-Reachability-Experiment' of https://github.com/kcharwood/AFNetworking into kcharwood-AFHTTPClient-Reachability-Experiment
Renaming AFNetworkReachabilityStatus and changing to bitmask

Fixing AFReachabilityCallback to give correct WiFi reachability value

Minor formatting and refactoring
Merge branch 'experimental-overrideable-http-operation-validation' into experimental-1.0RC1
Add setReachabilityStatusChangeBlock to AFHTTPClient initialization
Reverting network reachability status from bitmask to enum
Circumventing need to set initial network reachability status block to nil by wrapping callback in -startMonitoringNetworkReachability
-cStringUsingEncoding:NSUTF8Encoding -> -UTF8String
Constructing image in background queue
Updated Reachability to handle an IP Address or a Host name

Note this does not fix the issue with the status not being correctly
reported for a 3G connection.
Refactored starting up reachability
Refactored the Reachability status logic
Adding AFURLConnectionOperation -setShouldExecuteAsBackgroundTaskWithExpirationHandler: