postgres can't store RSA keys of length 2048 as primary keys

[ericchiang]

coreos/go-oidc#31 introduced a change that increased the default key length from 1024 to 2048 bytes. This causes a bug because the key is now too large to use as a primary key.

$ DEX_TEST_DSN='postgres://postgres@localhost/postgres?sslmode=disable' ./test-functional 
--- FAIL: TestDBPrivateKeySetRepoSetGet (1.07s)
    db_test.go:169: case 0: Unexpected error: pq: index row size 4008 exceeds maximum 2712 for index "key_pkey"
ERROR: error Decoding client creds 
ERROR: error Decoding client creds 
FAIL
FAIL    github.com/coreos/dex/functional    5.288s

Also, we're not running some functional tests through travis ci

[ericchiang]

The list of SHA1s effected by this bug.

$ git log --pretty=format:%H 9243107dab59844cbcec82b1e6a87f811dbbba7c..HEAD
71f502167821becc7d6900dd69bfad658ab16566
dc828825e6f9503511fdc823f450b597b8f641da
9f0487538d225d5484a89b205fea445a6b4e2080
6c0957666832d8de50906ab0d7dce0b0d716d8d7
96553c17939acbc46dfdd320f7bf8924eeedb27b
ad6e331860f8861e305d004342f6eba2424af2a7
1675acf21bbc001d46936624a2d80d5ce522d5a2
3776c74c157354385d0ac4dd37206bf31701b5d3
0f7fed8d5b94e5d182cc076daccf1c22d7935b71
630e5f2dcb9ea35b6ed4b8172f336cf3f1f57b64
a60a4d25bf33cf5aab3a531a1b363b8a4fe79bce
064b3bae47c0ac3d857f183f0ac6e6a8a71eb7be
c4767077aa74ab2a16f18195475f48160fc83bdf
5dd08a8dd44de6d3556366a7438d921869481d32
5192cac3421c734df77cd101248433b77b64dda0