Upload progress now works also for second file

- Sent bytes must be reseted before new upload, otherwise "onprogress" event "loaded" value provides sum of uploaded bytes (not just for the current upload, but all of them)
CB-6706: Relax dependency on file plugin
Merge branch 'wp8-loaded' of https://github.com/mhujer/cordova-plugin-file-transfer
CB-6802 Add license
ubuntu: support 'cdvfile' URI
CB-6127 Spanish and French Translations added. Github close #21
CB-6877 Updated version and RELEASENOTES.md for release 0.4.4
CB-6877 Incremented plugin version.
CB-6890: Fix pluginManager access for 4.0.x branch
CB-6781: add the exception text to the error object
CB-6781: Continue previous commit with one new instance (This closes #30)
CB-6781: Update new docs to match AlexNennker's changes in PR30