Android Hidden Camera Versions Save

Making autofocus and camera feature optional. (#39)

• Adding autofocus support

• Upgrading target api to 26.
• Applying sorting to picture sizes get highest/lowest resolutions
• Fixing issue #16 .

Changelog:

• Hidden camera activity and fragment release the instance of the camera as soon as activity/fragment goes in the pause state. [User HiddenCameraService to capture image in background.]
• Preventing simultaneous multiple images capturing.
• Fixing issue #12.
• Fixing issue #6.
• Fixing #7.
• Fixing #9.

Changes:

• Adding api to rotate the output image.
• Offloading output image processing to background thread to increase the responsiveness.

• Fixing issue #4 .

• #2 Bug fix.