[Mobile] annotation backend complete connections

[erkamkavak]

Following changes are made:

• context added to annotation
• annotation model and json conversions updated based on server
• annotations dto request added, response corrected
• annotation service connections made suitable for backend
• base service made suitable for different base urls
• annotation widget usages corrected

[umutdmr]

It is working but there is a minor issue. Annotations can be shown only if we refresh the related page. You have to fix this bug later. Good job!