Feminist activist Sandra Fluke made a pitch for Democrat Elizabeth Warren's Senate campaign in Northampton yesterday.  Fluke spoke to Smith College students gathered at a local cafe, calling this Senate race one of the last barriers between conservatives and women's rights.  Fluke rose to prominence in the women's rights movement in February when Republicans refused to let her testify before a House committee on insurance coverage for birth control.  Soon afterward, Rush Limbaugh called her a prostitute on his national talk show.