[BUGFIX] Enable Functional Tests for PSR-4 packages
[BUGFIX] Enable Functional Tests for PSR-4 packages

Packages with PSR-4 autoloading will not be able to work with
functional tests because two problems arise. First the
package namespace is prepended twice and second the path
contains an unnecessary backslash.

To avoid wrong amounts of backslashes we now use the path merging
utility to merge namespace parts instead of doing simple string
concatenation. Additionally a check is added for packages with
PSR-4 autoloading enabled.

Releaes: master, 2.3
Change-Id: Ic32b0720e93a5be49e8d76f64d43af8a704e0c60
Original-Commit-Hash: 0c2d4e2cf3dc0f8eedf48130930d2adb1118fe14

albe/flow-development-collection,bwaidelich/flow-development-collection,bwaidelich/flow-development-collection,gerhard-boden/flow-development-collection,chewbakartik/flow-development-collection,robertlemke/flow-development-collection,fcool/flow-development-collection,dfeyer/flow-development-collection,chewbakartik/flow-development-collection,albe/flow-development-collection,fcool/flow-development-collection,dlubitz/flow-development-collection,dfeyer/flow-development-collection,bwaidelich/flow-development-collection,fcool/flow-development-collection,kdambekalns/flow-development-collection,dfeyer/flow-development-collection,dlubitz/flow-development-collection,neos/flow-development-collection,kitsunet/flow-development-collection,kdambekalns/flow-development-collection,fcool/flow-development-collection,robertlemke/flow-development-collection,kdambekalns/flow-development-collection,aertmann/flow-development-collection,neos/flow-development-collection,daniellienert/flow-development-collection,kitsunet/flow-development-collection,daniellienert/flow-development-collection,gerhard-boden/flow-development-collection,chewbakartik/flow-development-collection,neos/flow-development-collection,mkeitsch/flow-development-collection,neos/flow-development-collection,dlubitz/flow-development-collection,dfeyer/flow-development-collection,albe/flow-development-collection,daniellienert/flow-development-collection,mkeitsch/flow-development-collection,aertmann/flow-development-collection,kdambekalns/flow-development-collection,aertmann/flow-development-collection,kitsunet/flow-development-collection,gerhard-boden/flow-development-collection,robertlemke/flow-development-collection,robertlemke/flow-development-collection,mkeitsch/flow-development-collection