Update src/mongo/tools/tool.cpp

SERVER-1994: Change the exit code from 0 when the tools are given a bad dbpath.  

EXIT_FAILURE could not be passed to dbexit, but EXIT_FS should be acceptable.

Tested on mongodump and mongorestore successfully.
SERVER-7329 bug in the getlasterror check at the end of mongoimport fixed.
SERVER-7329 also now checks at the beginning, after the first write, in addition to ad the end
SERVER-7329 treat duplicate key errors as nonerrors from an import job success pov
SERVER-7341 Make mongorestore correclty interpret backslash as a path separator.

This affects how mongorestore converts a path into a namespace name.
hookup google cpplint, and make "scons lint" run the checks we pass on now
including a few that i made pass

Conflicts:
	src/mongo/db/oplog.cpp
	src/mongo/db/repl/rs_initialsync.cpp
	src/mongo/util/hashtab.h
hook up our own IsTestFilename for cpplint
move lint code to its own directory
can pass a list of files to lint.py
SERVER-6961 Added system.indexes.bson back to mongodump for pre 2.2 mongorestore

Conflicts:
	src/mongo/tools/dump.cpp
	src/mongo/tools/restore.cpp
mongoimport more help text

Conflicts:
	src/mongo/tools/import.cpp
	src/mongo/tools/tool.cpp
SERVER-7534 mongorestore set default w=0 and call getLastError for w>0

Conflicts:
	src/mongo/tools/restore.cpp
Whitespace -- tabs to spaces
SERVER-2011 Fix handling of stdout vs stderr in mongoexport
SERVER-2011 Prevent mongoexport from writing to a file called '-'
SERVER-7721: require use of --db with --collection for mongodump
SERVER-8472 Change GLE default write concern back to fire-and-forget

Conflicts:
	src/mongo/tools/restore.cpp
SERVER-8367 Log error messages from GLE during mongorestore

Conflicts:
	src/mongo/tools/restore.cpp
SERVER-8525 - fix noobjcheck copy/paste-o in --help
SERVER-9061 Fix mongostat segfault when using auth with multiple hosts