SERVER-13582 increase stability of server6733.js by retrying replSetSyncFrom

(cherry picked from commit 9c39dd9b7be4cb0929f96671c424530d7608ac24)
SERVER-13562 limit and skip stages no longer return eof without calling work() on the child

Doing so could cause missing results for a tailable cursor.

(cherry picked from commit 9d1f365bf8f0c3d6192284cffab4e3927722e17c)
SERVER-13561 Improve wire API message validation

(cherry picked from commit 1490a4f30f7356c9b47cab77f17937f207f09551)
SERVER-13566 oplog start stage uses only 'ts' field as a filter

(cherry picked from commit 29d7dcd55a761cfa6a1a7e1586b80f9d1083b4f4)
Merge remote-tracking branch 'upstream/v2.6' into v2.6