Update to use GCC ARM Embedded 4.7-2012-q4-major.

Only working for OS X at this time.  Future commits will update the scripts to
install this latest set of GNU tools for Linux and Windows as well.

Changes include:
Updated mac_install script to pull down the pre-built OS X binaries now
available from launchpad.net site rather than versions built on my personal
Macintosh.  I do still update the GDB binaries to include patches that I have
made to use non-blocking I/O on OS X so that it works better with the virtual
USB serial port provided by the mbed interface chip.

Added NO_FLOAT_SCANF and NO_FLOAT_PRINTF make variable support.  These
variables allow for smaller versions of scanf() and printf( to be pulled in if
your application doesn't require floating point number support from these
functions.  This reduces the size of the resulting binary by several kilobytes.
Remove size optimized newlib libraries.

With the latest GNU tools, we use the nano newlib instead.
Update HelloWorld, Blink, and Ticker project makefiles to reduce binary size.

Updated makefiles for these projects to take advantage of the NO_FLOAT_SCANF
and NO_FLOAT_PRINTF variables to not explicitly pull in floating point
enabled versions of printf() and scanf().
Initial attempt to update linux_install script.

NOTE: Yet to be pulled down and tested on my Ubuntu environment.