Add support to enable reset on 1200 bps COM Port connect in board config...

In order to create custom bootloaders that allow for USB programming, there needs to be a flag that causes the uploader to initiate a 1200 bps connection and reset the target board. Currently, the names of bootloaders that use this mechanism (caterina) are hard coded into AvrdudeUploader.java making it impossible to fork the bootloaders without recompiling the IDE or overwriting an existing bootloader. This change adds a flag, "upload.reset_on_1200bps_com_port_connect" that allows the board spec to trigger the reset mechanism for custom bootloaders.

This change was motivated by my need to add a bootloader that worked with the 32u4 using the 8Mhz internal oscillator.