Implemented displaying images and linear gradient backgrounds

Implemented displaying images and linear gradient backgrounds (#22)

* feat(fe): display the images

* feat(fe): add linear gradient bg

* feat(be): create a simple endpoint for the cron job

Bug fixing

Default data, bug fixing, constant auth, data obfuscation  (#13)

* feat(BE): post default data to new users

* refactor(FE): remove default notes and autosaving, optimize and refactor code

* feat(auth): keep user authenticated until they manually logout

* feat: default data creation for existing users and labels bugs fix

* feat: obfuscate the data

New custom labels API

v1.2.1

Feature/custom labels api (#9)

Added new features.

v1.2.0

Added new features. (#7)

Added new features.

Fixed alert error issue. (#3)

* Made adding, choosing and deleting note types.

* Made better type input design.

* Made adding, deleting, choosing note category.

* Made multiple categories choice.

* Fixed removed labels issue.

* Made displaying categories on preview component.

* Made user data updation after categories or types change.

* Made expandable title input.

* Made adding a note from the main page.

* Made transition height change for add form on main page.

* Made better text editor.

* Made displaying end note and note time.

* Remade fetching notes.

* Made sidebar with all notes short preview.

* Made searching notes by title in sidebar.

* Made filter bar.

* Made search input.

* Made filtering by title name.

* Made filter modal and toggling values.

* Made filtering by type.

* Made filtering by type, categories and date.

* Made date filtering.

* Made importance filtering.

* Fixed adding custom labels issue.

* Fixed alert showing issue.

* Made sorting notes.

* Made adaptive layout for main page.

* Made adaptive layout for sidebar.

* Made adaptive layout for note form.

* Fixed little issues.

* Made different sidebar and filter bar state managing.

* Changed filtering notes.

* Fixed alert error issue.

v1.0.0

FIxed server url slash issue.