Merge pull request #17 from cefiar/master

Lots of general track clean-up.
RAMPS-FD schematic changes:
#3 replace C301, C302, C303 and C501 with ceramic 0805;
#4 change endstop connectors to 6x1 and 6x2 to allow key position
#9 change E-STOP connector to KK type;
#18 add 10k pulldowns on heater outputs from CPU
#19 change E-STOP buffers to HCT type to always drive FETs at 5V and remove inverting drivers on heater outputs;
#20 add 24LC256 I2C EEPROM
RAMPS-FD schematic: remove some redundant pulldowns;
add some explanatory notes;
update PDF
RAMPS-FD schematic: flip the endstop connector P802 for easier layout
Major layout changes to add extra components.
Addresses bug #20, bug #19, and bug #18.
Notable U1 relocation (adds room for Thermistor protection, less FET drive impedance).
Notable orientation change to Endstop connectors.
Increases in ground plane area on both Back and Front of PCB.
Board size increased to 95mm x 100mm (from 89mm x 100mm).