avoiding reassignment of nans when byteswapping

- mseed: see #485
adding missing data files for test
deb buildbots: make it possible to specify which fork/branch to build
deb building: if a fork is used we need to fetch tags from upstream to get reliable "git describe" results
Merge pull request #485 from mbyt/issue_485

mseed tests failing
adding changelog note for releasing
fixing download_url for dev version via easy_install
pep8
reverting commit 0ef60b8 as xml_doc gets closed too
API docs: add version number in some prominent places
fixes #489
Merge branch 'master' of https://github.com/obspy/obspy
fix for http://tests.obspy.org/?id=3712#0
second approach for fixing obspy.wav issue
last approach for obspy.wav
omg, fix for a fix for a fix - always use branches!
adding a reference for SEG2 file format
fix previous commit
Changes to the OSX installer.

Updated to the new ObsPy version.
New getScriptDirName() function.

Returns the directory of the current file in a robust way.