Finish tokenizer unit tests in test_syntax.

books/nand2tetris/projects/10_compiler_i_syntax_analysis/test/test_syntax.py
	-Add functions for all remaining token-types
	(`test_symbol_token()`, `test_integer_token()`, etc.).

10_compiler_i_syntax_analysis/jackcompiler/syntax/tokenizer.py
	-Tweak `INTEGER` token-type regex.