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