Meaning of "rolling stone"

In the song Papa Was a Rollin' Stone, what does rolling stone mean?

From the Shorter Oxford English Dictionary:

1. In the proverb A rolling stone gathers no moss, or variants of this
2. A rambler, wanderer

From Dictionary.com:

a restless or wandering person

From Urban Dictionary:

A person who likes to move often or is unwilling to settle down in one place or with one person or both. This phrase is based on the old saying "a rolling stone gathers no moss."

For more informations on the proverb, Wikipedia has a dedicated article which also mentions "Papa Was a Rollin' Stone" by The Temptations.