adding an adjacent geohash function

Adds the ability to calculate adjacent/surrounding geohashes so that neaby hashes can be retrieved.
Based on algorithm found in various codebases that seem to point back to David Troy's implementation in geohash-js which was published under a MIT copyright notice (see: https://github.com/davetroy/geohash-js)
Add a Travis-ci configuration

And modify test classes so they can be tested using Travis-CI.
add php 5.6
fix parsing of EMPTY wkt geometries
make failures output some useful information
fix typo
randomize testinput and fix some area tests
initialize variable str
Merge pull request #92 from mprins/adjacent-geohash

Add adjacent geohash function
Merge pull request #93 from mprins/travis-ci

Add a Travis-ci configuration
Triggering travis build
Everything now passes tests
Taggging version 1.2
Update README.md
Removing SCANDIR_SORT_NONE
Update README.md
Adding tests.php to testing, fixing 5.3
merge branch 'master' of github.com:phayes/geoPHP
Properly adding moving to test directoyr
Fixing filename typo in .travis.yml