make: comprehensive list of the boards' filesizes
make: add maketarget to to show the biggest obj files
make: show diffence in buildsizes for two folders
Add basic travis-ci integration

This PR adds the basic integration for [Travis CI][tci].

The config file `.travis.yml` tells the server to setup the basic build
system, and run `compile_test.py`. If not all  examples and tests could be
built, then the Travis CI integration adds a warning to "merge" button on
the bottom of the Github page.

Of course this integration makes little sense until #1049 is resolved,
because new bugs and old bugs cannot be told apart. Also (of course)
only because everything still builds, a PR still can intruduce a
multitude of runtime errors.

This integrations is meant to work additionally to our Jenkings. Users
can activate the test in their own RIOT forks to run the test before
opening a PR to master.

  [tci]: https://travis-ci.org/
Make implementation of hwtimer_spin() easier to read and understand
Merge pull request #1055 from Kijewski/travis-ci

Add basic travis-ci integration
msp430: Fix variable usage in cc430-rtc.c

Closes #967.
Automatically remove dups in `$(USEMODULE)`
drivers: fix includes in rtc.h for MSP430

The comment and the actual guard in `rtc.h` did not match.
If (as in "implication") the MCU is an MSP, then `sys/time.h` must be
included, to have `time_t`, `struct timeval`, …

Including the header file in any case should be safe, so I dropped the
guard altogether.
Merge pull request #1033 from Kijewski/buildsizes

make: comprehensive list of the boards' filesizes
add pthread condition variable implementation
Merge pull request #771 from BytesGalore/add_CV_module

pthread: Add condition variable module
added else branch in `pthread_exit()` to avoid calling explicit `return;`
however, this won't help to completely eliminate the warning on returning from a `noreturn` function
Merge pull request #1076 from BytesGalore/remove_return_from_noreturn_function

sys:posix:pthread removed explicit `return;` from `pthread_exit()`
Merge pull request #1073 from Kijewski/rtc-sys_time

drivers: fix includes in rtc.h for MSP430
ccnl: don't include transceiver and defaulttransceiver

This removes the duplicate include of the transceiver.
The transceiver module is a dependency of the
defaulttransceiver, so an explicite include is not needed

Follow up to #1053
Merge pull request #1082 from mehlis/ccnl-relay-transceiver-dup

ccnl: don't include transceiver and defaulttransceiver
Merge pull request #1002 from rousselk/fix-hwtimer-spin-wait

Enhance implementation of hwtimer_spin()
Merge pull request #1006 from Kijewski/issue-967

msp430: Fix variable usage in cc430-rtc.c
core: Remove `STATUS_TIMER_WAITING`

Closes #726.

The thread state `STATUS_TIMER_WAITING` is not used anymore.
This PR removes the value.
The number in `STATUS_ON_RUNQUEUE` is replaced by a reference.