Merge pull request #908 from akbargumbira/inasafe

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- Added extent validation on OSM Downloader
- Changed the bounding boxs text to west, east, north, and south instead of minimum latitude, maximum latitude, minimum longitude, and maximum longitude

- Tested by using it interactively on Linux Mint
- Unittests on safe_qgis.tools.test_osm_downloader are all passing on Linux Mint
[Backport] Indentation fixes.
Naming convention fixes
Fix more badly named vars
Merge pull request #914 from timlinux/develop

Naming convention fixes

Looking good. Thanks.