Clarify port forwarding sections

Fixed a line that I think was misplaced and expanded a bit the section "Port forwarding on steroid".
Increasing the number of open files by docker process.
Merge pull request #461 from SvenDowideit/amend-durdns-workaround-patch

Clarify port forwarding sections
Ensure network is up before starting ntpclient, sets and locks the system clock
Set default docker files limits.
Renaming ulimit env variable
Merge pull request #468 from boot2docker/fixclock

Fix the system clock sync
Merge pull request #466 from azukiapp/increasing_files

Increasing the number of open files by docker process.
change bootsync.sh to bootscript.sh and output console to /boot.log

change bootsync.sh to bootscript.sh
and create new bootsync.sh invoke the bootscript.sh ,logging info to
/boot.log ,so we can see what's wrong...
a few cleanups and use tee to log to screen and file.
start cleaning up some things