SERVER-15311 Never read from admin.system.new_users when looking for user documents.

The master branch no longer needs to support the 2.4-2.6 upgrade process, obviating the need for
this decision making.  Removing it will reduce the likelihood of future errors, and simplifies
storage concurrency control by removing the need for a multi-document atomic read.
SERVER-14668 DBRead should be acquiring S lock, not X

This fixes a bug introduced in commit
85e785fdce07dbb23b49220f4798f4627cf6af79.
SERVER-15327 disable warnings for unknown pragmas on Windows
SERVER-15182 remove tautological checks for "this" == NULL
SERVER-15305 remove undefined bool conversion error
SERVER-15184 supress warning about memset overwriting vtable ptr
SERVER-15183 suppress warning about fabs value truncation
SERVER-15306 (V8-3.25) suppress warning about "this" == NULL comparison
SERVER-15306 (V8) suppress warning about "this" == NULL comparison
SERVER-15317 Remove extraneous references to deprecated repl headers outside the repl directory.
SERVER-14184 Remove unused S2 macros that conflict on OS X Yosemite
SERVER-14100 explain for delete
SERVER-15062 more forceSync testing
SERVER-15062 add testing that nays do not prevent yeas
SERVER-15062 test majority means majority of voters not majority of nodes
SERVER-15062 fixed a double the in a comment
SERVER-15062 status ShutdownInProgress testing and fix for prepareElectResponse
SERVER-15062 improve syncSource testing
SERVER-15062 separate bad config and bad member tests in prepareFreshResponse testing
SERVER-15062 test name fix IAmArbiter