Update version to 2.7.5

Update version to 2.7.4

Update version to 2.7.3

Update version to 2.7.2

Create version file for 2.7.1

Merge pull request #1 from d0m84/bugfixes

substring is not a valid php function

Pull request #13: Develop

Merge in ZHUB/z-push from develop to release/2.6

* commit 'b84efc59ad09b809427d46aea59b1d33271e12ee':
  ZP-1626 . SafeGetContents is now able to unserialize with opt param. Removed SafeGetContentsUnserialize not more needed. Released under the Affero GNU General Public License (AGPL) version 3.
  ZP-1626 . Re-added SafeGetContents. Released under the Affero GNU General Public License (AGPL) version 3.

Pull request #13: Develop

Merge in ZHUB/z-push from develop to release/2.6

* commit 'b84efc59ad09b809427d46aea59b1d33271e12ee':
  ZP-1626 . SafeGetContents is now able to unserialize with opt param. Removed SafeGetContentsUnserialize not more needed. Released under the Affero GNU General Public License (AGPL) version 3.
  ZP-1626 . Re-added SafeGetContents. Released under the Affero GNU General Public License (AGPL) version 3.