Read the pid only once when stopping an instance

Review 718 by @mlucy
Closes #1115 again
Making the wording more clear, OTS review by @atnnn
config file parsing will now ignore options that apply to other modes of rethinkdb
added warning in must specify one of --directory or --file to import when unexpected files are found in the import directory
fixed a problem with nice_crash not logging errors properly, although it's pretty ugly right now
stopped using nice_crash in exceptions, just because it's a little silly, unified address in use exception catching, and fixed a bug in object_buffer_t when create() causes an exception
Removed nice_crash and nice_guarantee, since their use case is questionable at best.  Replaced with clean exits, or regular crashes.
Create /var/run/rethinkdb with the correct mode

Review 719 by @tryneus
Closes #1069
Tell launchpad to include the debug symbols

Review 731 by @tryneus
Closes #1130
Fix python version detection in proxy.sh

Review 732 by @tryneus
Closes #1165
Fix body for . ROTS by @mglukhovsky
1155_fix_wire_func_serialization
v1.7.2 draft release notes
Clarified #1109 description
Fixed typo
Update NOTES
fixed directory lock in --daemon mode
Merge v1.7.2 into v1.7.x

RethinkDB 1.7.2
draft NOTES for 1.7.3
gets embedded v8 compiling on 3.19