New helper function.

Added a new helper function converting a vector of unit length given in
dip and azimuth to a unit vector in the vertical, south, east coordinate
system.
Added arbitrary dip/azimuth rotation.

Added a new function that allows to specify the orientation of each
component seperately with dip and azimuth. The components do not have to
be orthogonal to each other it should work nonetheless. The output are
three new arrays, always oriented Up, North, East
Added rotate2ZNE method to obspy.xseed.parser.Parser

This enable the (very basic) fully automatic rotation of arbitrarily
oriented components to ZNE. Also renames the channels.
Added test for the Parser rotation method.
Added test files.
Updating changelog
Better docstrings.
Merge branch 'master' into rotations.

Resolved conflicting CHANGELOG.
decorator to add processing information to trace in a more general and
standardized way
use new decorator to add trace processing info
add a check for the station id to Network.get_response()
minor fixes for auto api docs
Merge remote-tracking branch 'upstream/releases'
refactoring obspy.station.inventory.Inventory.get_response()
basic tests for Inventory.get_response() and Network.get_response()
only call get_response() on Networks with matching id
Merge remote-tracking branch 'kaeufl/releases' into releases

Also some refactoring, flake8 etc.

Conflicts:
	obspy/station/inventory.py
Merge remote-tracking branch 'upstream/releases'
add @kaeufl to credits, see #724
Py3k: removing problematic future.builtins int

Was causing errors in docs