add capability detection for VHT and HE Beamformee STS

[joshschmelzle]

Reference issue #111.

This change adds detection for VHT Beamformee STS and HE Beamformee STS.

Text report example:

---------------------------------------------
 - Client MAC: 1a:b2:70:4e:cf:16
 - OUI manufacturer lookup: Apple (Randomized MAC)
 - Chipset lookup: Broadcom
 - Frequency band: 5 GHz
 - Capture channel: 165
---------------------------------------------
802.11k                Supported             
802.11r                Supported             
802.11v                Supported             
802.11w                Supported             
802.11n                Supported (2ss)       
802.11ac               Supported (2ss), MCS 0-9, [ ] 160 MHz, [X] SU BF, [ ] MU BF, Beamformee STS=6
802.11ax               Supported (2ss), MCS 0-11, [ ] 160 MHz, [ ] TWT, [ ] Punctured Preamble, [ ] SU Beamformer, [X] SU Beamformee, Beamformee STS=7, [ ] HE ER SU PPDU, [ ] UORA, [X] BSR
Max Power              21 dBm                
Supported Channels     36-64, 100-144, 149-165**
Number of Channels     25