Use UID to display appropriate user_data

[RitwikSingh28]

• Info about the issue : This PR will allow to display each user's individual info on profile_page.
• Name : Ritwik Singh
• GitHub ID : RitwikSingh28

Resolves #74

Approach

• Used FirebaseAuthentication class' getCurrentUser() method to extract current user's UID.
• Passed the obtained UID to getIndividualProfileData() method in FirebaseDatabase class to obtain user info

Changes Readjusted the fontSize of the heading on info_page.dart, to avoid overflowing pixels.

Screenshot

[RitwikSingh28]

@rani620 Please review my changes. :smiley: If any errors are found, kindly do let me know, otherwise please commit these changes into the master branch.

[rani620]

yaa sure