Update flatly.less
Update flatly.less

Because .item-summary is a p contained in an h4, it was using 1.1 line-height, which does not make for readability in large chunks of text. I applied the base line height to .item-summary.
josegonzalez/pullup,rickhanlonii/pullup,treygriffith/pullup,larvalabs/pullup,rickhanlonii/pullup,gitterHQ/pullup,gitterHQ/pullup,larvalabs/pullup,treygriffith/pullup,josegonzalez/pullup,rickhanlonii/pullup,larvalabs/pullup,gitterHQ/pullup,treygriffith/pullup,josegonzalez/pullup