[EXPORT][CoIDE] problem with missing linker script

- a missing linker script configures the scatter file option (linker
script path in CoIDE) to 'None' not to ''
[EXPORT][CoIDE] [DISCO_407] and [NUCLEO_F4x1] memory areas

The templates now contains the memory areas preconfigured as they are
used in linker scripts. When the CoIDE linker option 'Use memory layout
from memory window' is manually switch on the correct memory layout is
already there.
Merge pull request #516 from ohagendorf/develop_coide

[EXPORT]  CoIDE - linker script - none fix, memory areas for nucleo 4x1 and disco 407