descrive Characteristics of F9 Microkernel in brief
README: add 'Quick Start' and 'Build Configuration' sections

Fixes #6
thread: fix reference citation
README: update the characteristics list
move linker script to directory platform
rules: don't hardcode libgcc
f9.ld: remove trailing whilespace
add STM32F4DISCOVERY instructions about terminal emulators
rename toolchain build script for consistency
update L4 microkernel information
README: revise system call descriptions
update STM32F4DISCOVERY board info
update configurations
move UART device definition to board header
avoid duplicated NVIC entries for STM32F4

Fixes #15
update bitmap location in linker script

Fixes #10
Merge pull request #16 from arcbbb/fix-bitmap

update bitmap location in linker script
add arcbbb in contributor list
remove cpsid/cpsie from irq_{save, return}
add initialization to handler priority