Custom Alignment for headers and body

<img width="394" alt="kxtells_gotabulate__Golang_clone_of_Python_tabulate__a_table_utility_" src="https://user-images.githubusercontent.com/5339274/168185531-4469de08-5e49-4689-a84c-9ce0ed8352c5.png">

Default alignment is for the 1st Column is align Left and for the rest is align right. 
We should add option to align all in left, right or middle.