Reflected the changes in the API of aggregate losses in risklib (https://bugs.launchpad.net/openquake/+bug/1096880)
PEP8-consistency changes
Big simplification of GroundMotionValuesGetter
export/hazard:

Added handling for the case where the GMPE logic tree contains two
branching levels. In this situation, the export dir is a concatentation
of the GMPE names, joined by _.
tests/export/hazard_test:

Added a test for the error described by
https://bugs.launchpad.net/openquake/+bug/1098518.
Merge pull request #1000 from larsbutler/fix-gmpe-export-dir

Fix result export with multiple branching levels

[r=gvallarelli] [f=1098518]
Added a numerical tolerance to min_dist
bin/openquake:

bin/openquake now sets the OQ_NO_DISTRIBUTE envvar when the
`--no-distribute` cmd line switch is specified.
__init__:

Added a util function for checking the state of the OQ_NO_DISTRIBUTE envvar.
calcs/base:

`execute` now logs a WARNING when calculation distribution is disabled.
calcs/base:

`queue_next` now executes tasks as plain functions if OQ_NO_DISTRIBUTE is set.
engine2:

`_switch_to_job_phase` now checks if OQ_NO_DISTRIBUTE is set. If it is,
don't check the presence of worker nodes. (In the default case, an absence
of workers will cause the calculation to abort immediately. In the
non-distributed case, this check is skipped.)
calcs/hazard/classical/core:

Mean/quantile post-processing code now takes into account the "no-distribute"
option.
calcs/hazard/classical/post_processing:

Hazard map post processing now takes into account the "no-distribute"
option.
qa_tests/_utils:

Hazard QA tests turn off distribution by default.
calcs/hazard/general:

A small fix for https://bugs.launchpad.net/openquake/+bug/1098658.
Merge pull request #1003 from larsbutler/fix-1098658

Fix for bug # 1098658

[r=larsbutler] [f=1098658]
qa_tests/_utils:

Cleaner patching for `OQ_NO_DISTRIBUTE` envvar.
Merge pull request #999 from gem/1098191

Write an hazard getter for the risk scenario calculator, first step: refactored the current hazard getter for the GMF
tests/openquake_test:

Added some tests for `no_distribute()`.