[README.md] some changes and additions

Changed web addresses from mbed.org to developer.mbed.org, added some
Nucleo and one Discovery board, reorder of the Nucleo boards depending
on M0, M3, M4.
[README.md] some more changes and additions

Some more web addresses changes and added CoIDE as toolchain.
[HAL][ARCH_MAX] add pin names - D14 and D15
README.md add boards of Seeed Arch series
Adjusted pin assignment for the BLE Nano board.
Merge pull request #545 from ohagendorf/master

README.md - some changes and additions
Merge branch 'stm32f407' of github.com:xiongyihui/mbed into xiongyihui-stm32f407

Conflicts:
	README.md
Merge branch 'xiongyihui-stm32f407'
Clean up and fixes.
Merge pull request #548 from Cheong2K/master

HAL: BLE Nano - pin corrections for the BLE Nano board (D0-D7)