Break travis compile tests into smaller builds

* The previous 01-compile test has been renamed to compile-base. It
  now only tests {msp430, avr, native}-based platforms
* New test builds for arm-based and 8051-based ports (one build per arch)
* Only install arm-none-eabi, sdcc and srecord for the builds which need
  them. This will somewhat speed up all other tests
* Test er-rest-example and webserver-ipv6 for the cc2538
* An erroneous comment was fixed and another comment was somewhat
  clarified
Don't try to tail *.testlog after non-sim tests

Fixes #247
Add support for verbosity control
Adjust a config define to its new name
Update readme references and tool download URLs
Read IEEE address from InfoPage by default
gitignore CC2538dk firmwares
Merge pull request #326 from g-oikonomou/cc2538-contikimac

Adjust a config define to its new name
Merge pull request #325 from g-oikonomou/cc2538-tools-release

CC2538 IEEE address and README updates
Merge pull request #327 from g-oikonomou/cc2538-build-verbosity

Add support for verbosity control
Merge pull request #324 from g-oikonomou/cc2538-gitignore

gitignore CC2538dk firmwares
Merge pull request #323 from g-oikonomou/smaller-travis-builds

Travis: Multiple Smaller Compile Builds and a Fix
Make the CC2538 UART driver more configurable

* We can now very easily switch between UART0 and UART1 through a define
* We can also configure the UART RX and TX port/pin through defines
Remove leftover make targets

The sensinode platform does not support .upload and .serialdump
Their presence in the makefile has confused in the past confused
some users. This commit removes them

The commit also removes the $(OBJECTDIR)/%.rel: %.cS recipe which
is not used by either 8051 platform and is probably broken anyway,
since it has been unmaintained for years
Auto-enable SLIP for 8051-based platforms
Move SLIP interface define to project-conf
Disable example-defined putchar for 8051 platforms
Increase 8051 plaform configurability
No longer build rpl-of0 for Sensinodes
Change the cc2531 usb stick descriptor

The CC2531 USB stick now identifies itself as a
'Texas Instruments CC2531 USB Dongle' and uses a
TI-assigmed VID:PID. The VID:PID is now configurable
in contiki- or project-conf.h