(Bug 34383) Canonical namespace names

For more details, see [1].

https://bugzilla.wikimedia.org/show_bug.cgi?id=34383
Re-introduce enableSemantics() to avoid Notice: Use of undefined constant SMW_NS_PROPERTY

After smwgNamespaceIndex and $smwgNamespace are set enableSemantics() is
called to specify SMW related custom namespaces.

## Example LocalSettings
$smwgNamespaceIndex = 104;
enableSemantics( 'http://example.org/id/', true );
...
Some minor clean-up
Use --prefer-source because of GitHub quota

[1] showed Composer\Downloader\TransportException during Travis initialization
which according to [2] is because of a GitHub quota

[1] https://github.com/SemanticMediaWiki/SemanticMediaWiki/pull/47

[2] https://github.com/travis-ci/travis-core/issues/186
Merge pull request #50 from SemanticMediaWiki/travis

Use --prefer-source because of GitHub quota
Merge pull request #47 from SemanticMediaWiki/namespaces

(Bug 34383) Canonical namespace names
Update coverage badge
Travis path issue
Merge pull request #51 from SemanticMediaWiki/travis

SetupTest travis path issue
Avoid issues prior Composer MW 1.22 installation

If a user runs Composer from a local SMW directory, the Composer autoload prior MW 1.22
is run at later point and to ensure LocalSettings remains untouched we register
'SMW\NamespaceManager' to enable enableSemantics() to work its magic.

Class 'SMW\NamespaceManager' not found in ...\includes\GlobalFunctions.php on line 287

Enables to run composer install/update from the SMW root directory for MW 1.19
without the need to change LocalSettings or to install an extra extension.
Merge pull request #52 from SemanticMediaWiki/composer

Avoid issues prior Composer MW 1.22 installation
NS usage
Merge branch 'master' of ssh://review/mediawiki/extensions/SemanticMediaWiki