Create Unit tests

[Edios]

Create unit test for modules:

• Numpad Keyboard module
• Trie engine
• Single tap Keyboard module
• Object need to be adjusted for using word processor and keyboard writter
• T9 Keyboard module
• Probably need to separate t9_engine here, then create tests
• Word processor
• Initial sketch done
• Keyboard writer
• Tests can be implemented with mocking Controller (input by keyboard)

[Edios]

Trie module tests done in: #1

[Edios]

Numpad keyboard and trie engine tests:
PR: #14