Code cleanup: fixes based on findbugs 3.0 findings

Running findbugs 3.0 on the code base provided some useful
cleanup suggestions, and some direct bugs which should be fixed.
This commit fixes the most obvious ones, there are still some
findbugs findings left that should be investigated more.
Findbugs: add findbugs reporting
Code cleanup: more fixes based on findbugs findings

Fixes based on findbugs reports.
Update junit version, and add junit test for Utils class.
Merge pull request #93 from asv000/master

Implemented file/folder copy and move operation
Merge pull request #92 from alfh/fix_findbugs_findings

Code cleanup: fixes based on findbugs 3.0 findings
Merge pull request #95 from asv000/master

fix a bug of copy and move function,change a file name, implement taking photo function
refactor out SeafilePathChooser

It can be used in both ShareToSeafileActivity and file
copy/move operation
add icons for copy/move action
fixed move a folder
improve copy/move operations

- don't allow copy a folder into its subfolder
- don't allow copy to a encrypted libraries
remove unuseful code
updated i18n
update verison to 1.0.0